I could be wrong, but I don't think there were any commits after build #6, let alone #7. Last commits that I see were early morning 2/23/11 and build 6 happened late evening 2/23/11 - so I'm pretty sure #6 and #7 are identical, unless they just stopped tweeting changes.
soonsoon: when code is added to the main branch of the cyanogen project, it's been "committed". As each piece of code is committed, a more-or-less cryptic tweet goes out on @cmsrc summarizing the change. Unless you're a dev, the changes can be hard to understand, but you can usually get at least a general idea of what's being worked on.
It looks like the last time new code was committed was 2 am last Wednesday, so it looks like nothing's changed since then.