A first release candidate for the 0.4 version has been released. At the moment there are binaries for windows and linux (Mac hopefully coming soon) plus sources.
Important new features: SuperTuxKart is now using bullet physics, which significantly improves collision handling. Additionally, it includes a new kart (wilber), improvements to existing tracks, faster AI karts, some new music, and the option to 'look back'.
Please give it a try. Feedback is welcome.