Please add an automatic download of the most recent snapshot to catalyst. Proposed implementation: Enhance the "snapshot" item handler to understand URLs and point it to $SNAPSHOT. On each run of catalyst, the file $SNAPSHOT.md5 is downloaded and the currently used snapshot will be compared against the md5sum. If it doesn't match, redownload $SNAPSHOT.
According to Chris, this can cause issues with gcc being recompiled etc. If you want to fight for this to be included convince him.