I just threw in my Knoppix 4.0 CD into the drive of my Mac Mini (see notes on left).
It booted into KDE, Mouse detected (Microsoft Wireless Mouse), keyboard detected (
i-rocks). No buffer issues, unable to detect hard drive (partitioned FAT32 and OS X via bootcamp).
found USB, Firewire, video card, not sure about sound. Dual Chip Board detected.
SLAX bootup: Sound works, video card works.. I get a minor lag when moving mouse. auto-mounted hard drives are sda3 (my Fat32 bootcamp partition). Not sure about dual core, not sure about OS X HDD detection (doubt it).
Slackware 10.2: No luck. kernel panic right after bootup.
Haven't bothered installing a linux distro on my mac mini just yet, and yeah.. it appears the "base.i" type kernels for PC boards work just fine with mactels, the problem you run into is device detection is kind of hit or miss.
SLAX sounds like they'll be including proper Mac Mini support after a post I had on their place. Personally, I think SLAX is the way to go for down and dirty linux. :]