I finally had to reboot my Gentoo box today. My uptime as of reboot:
315 days, 54 min
Not spectacular, but not bad for a dust-covered desktop machine, and it probably could've gone another 300 days or so. I only had to reboot because I bought another 500GB hard drive.
Funny thing about rebooting after that long, you have no idea what's going to happen. I finally unmasked and compiled a newer kernel, and there were quite a few new options and features in there to root through. My disk hadn't been
fscked for 396 days, and after rebooting and 15 minutes of grinding away, it found a few dozen orphaned inodes. A few init scripts having to do with modules gave me some warnings, but I fixed that up.
But I think I can spare an hour every year or two to update my system.