In my mythtv kernel configuration HOWTO, there are several kernel modules that must be re-emerged after a new kernel is installed. [ivtv] was particularly troublesome, because each version of ivtv only applied to a specific kernel version. To install a new kernel, you’d have to first make sure you could get the right version of [ivtv], typically through version-specific masking (pita), then install the kernel, then re-install [ivtv], hoping you didn’t run into any problems. So it’s a lot easier now that [ivtv] is included in the kernel – just configure it into the kernel and you’re good to go. See gentoo’s [ivtv] web page for details, it’s just starting to get documented. But gentoo packages are all good to go! Yay gentoo!