nouveau, the project for creating a free 3D linux driver for nvidia cards, recently got first support for real 3D applications with gallium on some NV4X cards (see Nouveau Companion 36). Today I got it working on a friends machine.

Here you can see an openarena benchmark (also uploaded on youtube). It got 55 fps, which is far away from the nvidia binary driver yet (178 fps), but at least more than my r200 setup (32 fps).

For the brave ones, here's a quick and dirty howto for Gentoo:
a) Get the nouveau overlay with svn co https://svn.hboeck.de/nouveau-overlay and add it to PORTDIR_OVERLAY in make.conf.
b) The nouveau-overlay won't install the nouveau/gallium-branch of mesa. Get my overlay with svn co https://svn.hboeck.de/overlay and also add that to your PORTDIR_OVERLAY (I'll try to contact the nouveau-overlay developer if we can merge this).
b) Add media-libs/mesa, x11-base/x11-drm, x11-libs/libdrm and x11-drivers/xf86-video-nouveau to /etc/portage/package.keywords and merge them.
c) If you've been running the nvidia binary driver, eselect opengl set xorg-x11, change the graphics driver in xorg.conf to nouveau, rmmod nvidia (if you've been running the binary driver), modprobe nouveau and start X.
d) Have fun!

Note: The nouveau developers consider gallium completely unsupported at the moment and don't want to get end-user bugs. If it runs, fine, if not, don't nag them with it.

Binary drivers are imho a hughe problem for free software. Nvidia, leading graphics company, has produced binary linux drivers for a long time and there was no way to get free software 3D-support on their cards.
A group of people is working at the moment on a free nvidia driver, the project is called nouveau. I now had a chance to test the nouveau driver on a nvidia card (nv43). It doesn't do much at the moment, but at least it runs glxgears almost smooth.

It's nice to see development on that front. We made a small video of glxgears running on nouveau. Oh, for all those who can't play theora, I put it up on youtube (but seriously, was just curious how youtube works and if it accepts theora).

Some experimental nouveau-ebuilds, maintained by pq from the nouveau-project, are here:
svn co https://svn.hboeck.de/nouveau-overlay

Another update from the X-funky-and-cool-front: With some Patches from Kristian Høgsberg, I got compiz running with aiglx.

For those who don't know: Compiz is a combined window/composite manager that was released together with xgl earlier this year. aiglx is another approach to get 3D-accelerated Desktops on Linux/Xorg.

I've merged the appropriate (very experimental stuff, big fat warning!) gentoo packages into my overlay. For all non-gentooers: You are on your own, but you can grab Kristian's patches here. Update: Kristian told me that Fedora Rawhide users are also lucky.

You can get it with
svn co http://svn.hboeck.de/xgl-overlay
(It's still called xgl-overlay, although it should probably be named »various-funky-x-stuff« or so, but I was too lazy to rename it)

To install it, check it out like above, put the path into your PORTDIR_OVERLAY-var in make.conf. Then re-merge libdrm, mesa, xorg-server and compiz (all ~x86). You can also merge experimental libcm/metacity-packages (metacity with 3d-effects), therefore add xcomposite to your USE-flags and merge metacity-2.15.5.

To start compiz on aiglx (that means »normal« X):
LIBGL_ALWAYS_INDIRECT=1 compiz --replace --strict-binding move resize minimize place decoration wobbly cube rotate scale switcher zoom &
gnome-window-decorator
(replace plugins with anything you want, the LIBGL-var and strict-binding are required for running in aiglx, this should be automatically detected soon)

For metacity use:
USE_WOBBLY=1 metacity --replace

As before, there is still a package for xgl, so you now can try both.