Well folks, sorry about the downtime
The database migration in RC2 was written slightly wrong in such a way that it locked up the database, and since ours is really big, server wasn't able to handle it.
I implemented a fix for the migration and tagged 1.6.0rc3, to be upgraded to instead of rc2. It's sad this wasn't caught during testing 'cause the testing databases aren't big enough. If you already upgraded to rc2 without problems, good for you, you don't have to do anything.