"Basically, LibCheck analyzes a version of a library, and compares it to another version of the same library. It then reports the differences ... in a list, available as HTML or xml. ...the list is presented as a set of removed, and added methods. When we can detect that change in question is a breaking change (and generally, removals are likely candidates!), we color the change red.
Now if you're used to the change report we put out periodically with a release, you now have the tool that generates that list! "
(via BCL Blog)
Update:
Not to scare anyone , but this guy has had a very bad experience while running the LibCheck build file- His windows XP installation got corrupted.. I'm not saying (neither is he) that the build caused this somehow, but just to be on the safe side - don't run this anywhere important unless you're sure it's ok and stable..