Some MogileFS instances are "too big to fail (or migrate)" :)
The other thing is MogileFS is really simple (IMHO) for a small group to
handle; big, shiny, corporate Open Source projects put me off...
About Perlbal: what non-MogileFS users are these days?
I can help on the MogileFS-side using any plain-text mailing list
including this one.
But my involvement will be limited since I'm completely uncomfortable
with corporate-sponsored things like GitHub and GoogleCode being
involved with infrastructure APIs (bug-trackers, pull-request messaging,
etc...)