I have a Hauppaughe WinTV Radio TV card, which has worked quite well since FC4. As of updating to kernel-2.6.17-1.2139_FC5 via yum, the card has gone quiet. Took me a bit by suprised, luckily, I remembered having done an update, and the kernel package was teh only relevant update in my yum log. Rebooting with the previous kernel restored my sound.
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=197424
-- To be updated...