The bulk of the software about which I care has been rebuilt now. About the only thing that's still both major and missing is the MythTV support for the ATI TV Wonder Pro. Weird thing is that I keep reading about how this card doesn't work properly, but with the bytesex.org patches it's been working perfectly well for me (including audio) with the 2.6.11 kernels.
The new Gentoo instance, of course, is currently using a 2.6.12 kernel. Unlike with the old instance where 2.6.12 was missing audio, but worked otherwise, with the new instance 2.6.12 actually causes a crash in the back-end whenever I change channels (LiveTV).
I'm now in the process of building a 2.6.11 kernel with the patch-set. Hopefully that will get me back up and running and I can worry about the 2.6.12 problems some other... year.