Comment 2 for bug 751644

Same behavior here - here's what my dmesg shows on card insertion:

[ 86.537936] sd 4:0:0:0: [sdc] 31457280 512-byte logical blocks: (16.1 GB/15.0 GiB)
[ 86.539926] sd 4:0:0:0: [sdc] No Caching mode page present
[ 86.539931] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[ 86.543804] sd 4:0:0:0: [sdc] No Caching mode page present
[ 86.543812] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[ 86.544743] sdc: sdc1

Then nothing. The card worked on the Alpha, and it worked in 10.10 (and even in the beta over the weekend, prior to updates).
This is on an Acer 5742, via the integrated reader.

Plugging the same card into a USB reader it pops right up.