(Not my idea — suggested by a conversation on
#gnome.)
Big sites like Sourceforge that need to support CVS development with lots of users and projects would find it useful if checkins were replicated automatically across a cluster of CVS servers. It may be possible to arrange this using CVS hooks: make a checkin acquire the write lock on all of the CVS servers in the cluster, then sync the changes (using rsync, cvsup or somesuch) to all the other servers once it's complete.