This just started happening for me recently as well. Pithos was working for a while. This is a Kubuntu 11.04 machine with KDE 4.7.00. PulseAudio, of course.  My pithos -v output is similar to the original reporters.

I don't know if this helps, but if I strace the process, after it starts loads, and buffers, it generates this approximately once per second:

If you want the full strace output, let me know.

clock_gettime(CLOCK_MONOTONIC, {74127, 65768916}) = 0
clock_gettime(CLOCK_MONOTONIC, {74127, 66280294}) = 0
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {74127, 66716243}) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=13, events=POLLIN}, {fd=14, events=POLLIN}], 6, 0) = 0 (Timeout)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {74127, 68494473}) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=13, events=POLLIN}, {fd=14, events=POLLIN}], 6, 0) = 0 (Timeout)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"5\30\4\0A\10\240\6\270\0\240\6\337\1d\0\225\4\5\0B\10\240\6A\10\240\6*\0\0\0"..., 8820}, {NULL, 0}, {"", 0}], 3) = 8820
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {74127, 76855389}) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=13, events=POLLIN}, {fd=14, events=POLLIN}], 6, 0) = 1 ([{fd=4, revents=POLLIN}])
read(4, "g\2\332$\270\0\240\6\271\0\240\6\344\26k\4\0\0\0\0\337\1d\0\5\0008\0\337\0012\1", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\224\5\4\0Q\10\240\6\0\0\0\0\337\1d\0\231\3\4\0\271\0\240\6Q\10\240\6\0\0\0\0"..., 40}, {NULL, 0}, {"", 0}], 3) = 40
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {74127, 78061058}) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=13, events=POLLIN}, {fd=14, events=POLLIN}], 6, 0) = 0 (Timeout)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"5\30\4\0R\10\240\6z\0\240\6\337\1d\0\225\4\5\0S\10\240\6R\10\240\6*\0\0\0"..., 88}, {NULL, 0}, {"", 0}], 3) = 88
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1 \343$\1\0\0\0\4\0\0\0\0\0\0\0\1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 36
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\24\0\6\0z\0\240\6\300\1\0\0\6\0\0\0\0\0\0\0\377\377\377\177", 24}, {NULL, 0}, {"", 0}], 3) = 24
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1 \344$\4\0\0\0\6\0\0\0\0\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 48
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\16\0\2\0z\0\240\6", 8}, {NULL, 0}, {"", 0}], 3) = 8
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\30\345$\0\0\0\0X\1\0\0\0\0\0\0\364\1h\1\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"(\0\4\0z\0\240\6X\1\0\0\0\0\0\0", 16}, {NULL, 0}, {"", 0}], 3) = 16
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\1\346$\0\0\0\0\205c\266\1\3\0\27\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\225\10\t\0\3\0\240\6\312\0\240\6\0\0\0\0S\10\240\6\2\0008\0\0\0\0\0\0\0\0\0"..., 96}, {NULL, 0}, {"", 0}], 3) = 96
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1 \351$\1\0\0\0\4\0\0\0\0\0\0\0\1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 36
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\24\0\6\0z\0\240\6\300\1\0\0\6\0\0\0\0\0\0\0\377\377\377\177", 24}, {NULL, 0}, {"", 0}], 3) = 24
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1 \352$\4\0\0\0\6\0\0\0\0\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 48
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\16\0\2\0z\0\240\6", 8}, {NULL, 0}, {"", 0}], 3) = 8
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\30\353$\0\0\0\0X\1\0\0\0\0\0\0\364\1h\1\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"(\0\4\0z\0\240\6X\1\0\0\0\0\0\0", 16}, {NULL, 0}, {"", 0}], 3) = 16
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\1\354$\0\0\0\0\205c\266\1\3\0\27\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"5\10\4\0T\10\240\6R\10\240\6\337\1d\0\225\4\5\0U\10\240\6T\10\240\6$\0\0\0"..., 428}, {NULL, 0}, {"", 0}], 3) = 428
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\30\376$\0\0\0\0X\1\0\0\2\0!\0\337\0012\1\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\225\4\6\0W\10\240\6\270\0\240\6*\0\0\0\0\1\0\0\1\0\0\0\225\10\t\0\3\0\0\0"..., 84}, {NULL, 0}, {"", 0}], 3) = 84
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1 \1%\4\0\0\0\6\0\0\0\0\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096) = 48
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"\16\4\2\0z\0\240\6", 8}, {NULL, 0}, {"", 0}], 3) = 8
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\30\2%\0\0\0\0X\1\0\0\0\0\0\0\364\1h\1\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"(\4\4\0z\0\240\6X\1\0\0\0\0\0\0", 16}, {NULL, 0}, {"", 0}], 3) = 16
poll([{fd=4, events=POLLIN}], 1, -1)    = 1 ([{fd=4, revents=POLLIN}])
read(4, "\1\1\3%\0\0\0\0\205c\266\1\3\0\27\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 4096) = 32
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=4, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=4, revents=POLLOUT}])
writev(4, [{"5\10\4\0X\10\240\6R\10\240\6\337\1d\0\225\4\5\0Y\10\240\6X\10\240\6$\0\0\0"..., 788}, {NULL, 0}, {"", 0}], 3) = 788
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {74127, 91318957}) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=13, events=POLLIN}, {fd=14, events=POLLIN}], 6, 0) = 0 (Timeout)
clock_gettime(CLOCK_MONOTONIC, {74127, 91619764}) = 0
clock_gettime(CLOCK_MONOTONIC, {74127, 91736957}) = 0
read(4, 0x92f5298, 4096)                = -1 EAGAIN (Resource temporarily unavailable)
clock_gettime(CLOCK_MONOTONIC, {74127, 91983078}) = 0
poll([{fd=5, events=POLLIN}, {fd=4, events=POLLIN}, {fd=3, events=POLLIN}, {fd=7, events=POLLIN}, {fd=13, events=POLLIN}, {fd=14, events=POLLIN}], 6, 972