I recently did some work with one of the best features of the upcoming R2 release of Windows Server 2003, DFS Replication.  DFS Replication is the successor to FRS and it has a lot of goodness about it it, primarily the fact that it does delta replication.  In other words, if you have a 1GB file that you change 6K in, we now only replicate that 6K (plus some inconsequential amount of state information) rather than the entire 1GB file like FRS does.  This is great for branch office scenarios or anywhere else you want to mirror a directory across multiple systems.