Xsan 1.0.1 Update
I think Scott is psychic. He mentions Xsan in what's the first I've heard of anything Xsan-related in months, and voila! There's an Xsan update in the pipeline. Crazy.
In any case, if you have, use, and love Xsan, make sure you grab Xsan Update 1.0.1. According to Apple, "The 1.0.1 Update delivers overall improved reliability for Xsan and is recommended for all systems," including improvements "using the 'mv' command to move files from Xsan (ACFS) to Mac OS Extended
(HFS+) volumes . . . saving files over 4GB via SMB/CIFS to an Xsan volume hosted on Mac OS X Server," as well as "greater server stability when resharing Xsan volumes via NFS," all while "eliminating spontaneous metadata controller failovers that can result in slow file performance." I think that means that it is better. Get it.