@PeterT
That would be good news (no changes in the database).
I use calibre to collect my books, COPS to serve them and Marvin (iOS app) to read them.
On the Marvin forum it was stated that Marvin does not work (for now) with calibre 2.0. I could not find out if it was a database or interface problem, so to be better safe than sorry, I planned not to upgrade calibre for the time being.