I'm a (mostly) happy user of a Linux-only (Gentoo) IBM Thinkpad T43.
Currently I'm running Compiz-Fusion 0.7.8... :-) which kind of proves that the fglrx driver works. Performance is not so great though, possibly because of the indirect rendering required. Driver version 8.6 works stable.
Note to ATI: please, please, please implement GLX_EXT_texture_from_pixmap!!!
Second note: Why, oh why, do newer driver ebuilds require X 1.5?!?