I am also a great fan of github. But my main question was not on the repository, but on the test environment. Sorry for the confusion.

If I have 4 developers working on a project using ELGG and they have setup different source base, but uses the same database instance, is there any way we can keep them in sync. At certain point of time, their sources will have their own features for time being and can the data and cache be kept in sync?

Apologies again if this sounds stupid.

u r looking for mysql database versioning control. there's (commercial) tools around to manage 'svn' control of schemas. svn`ing the actual data ? but - much more work will be involved to handle this - mysql 'data' is not straight-forward text to be managed just like schemas.

Is there a reason they all need to be working on the same database?  Why not have separate working installations for unstable development code, then push stable code (from a repo tag for instance) to a central test installation.  Databases can be sync'd quickly and easily enough... Actually developing on the same installation with other people is extremely annoying, you get things breaking, random var_dumps showing up out of nowhere, etc.