I'd be interested to know if there's any download links for these GPU drivers. I ordered an RP this week, Gentoo is the distribution I'd be interested to go forward with.
That's an interesting question. If you go back a bit on the blog, you'll find a post (I don't have the link offhand) with a diagram describing the various pieces that make up the RasPi's "drivers". For starters, you can already get the specially patched kernel sources and the GPU boot firmware here: https://github.com/raspberrypi/
As for the GL libraries to make the GPU go, there's a link somewhere around here to a set of the compiled libraries with hardfloat support, but it seemed like Chromatix and dom were working out the bugs, so I don't know what state they were in. You can also rip them out of the already-released Debian image.
We're interested in making ebuilds out of everything already available on that github page, plus the libraries, and making an overlay or somesuch to enable easy access. Stay tuned.