Source code: http://hg.mozilla.org/services/sync-server Instructions: https://wiki.mozilla.org/Labs/Weave/Sync/1.1/Setup
Edit: Also the link seems to be outdated.
http://tobyelliott.wordpress.com/2011/03/25/updating-and-dep...
The PHP "minimal" server is going away in the future, as the Python server becomes better-supported and easier to set up. For now, however, the minimal server is usable and current; the latest version was released just last week.
(The Python implementation will eventually replace the PHP implementation in production as well.)
Source code: http://hg.mozilla.org/services/sync-server Instructions: https://wiki.mozilla.org/Labs/Weave/Sync/1.1/Setup