A few days ago MySQL 5.1.42 got released and it is now available with builds for MacOS X 10.6 (Snow Leopard)! The download website doesn’t show it yet, but if you are burning to try, you can get it from the mirror-picking-website.
As usual, don’t forget to checkout the changelog before upgrading!
If you want to compile it yourself, and need a universal binary, you could try my previous blog entry «Building MySQL universal binaries using MacOS X 10.6 (Snow Leopard)».