I installed Ubuntu 12.10 32bit in a VM with Inkscape 0.48.3.1 r9886 from the Ubuntu repos. There I have the same problem as described above.
On Windows 7 64bit with Inkscape 0.48.4 r9939 it doesn't work quite as expected, but with a different behavior:
* "Aller", "Aller Light" and "Aller Display" are in the list but I only can choose "Aller Light" from the font dialog.
* If I try to choose "Aller Light" from the list, "Aller" gets displayed/choosen instead.
I tested a bit further:
I installed Ubuntu 12.10 32bit in a VM with Inkscape 0.48.3.1 r9886 from the Ubuntu repos. There I have the same problem as described above.
On Windows 7 64bit with Inkscape 0.48.4 r9939 it doesn't work quite as expected, but with a different behavior:
* "Aller", "Aller Light" and "Aller Display" are in the list but I only can choose "Aller Light" from the font dialog.
* If I try to choose "Aller Light" from the list, "Aller" gets displayed/choosen instead.