Distributed Version Control. Huh. What if we lived in some new world where XML was considered a universal format, and a distributed version control system (which may just happen to be better at textual formats (such as XML) than binary nonsense) would get you everything you needed for both transactional action (such as rollbacks) and solve a bunch of those problems proprietary replication schemes seem to run into...
why, you might not even need a database at all. Sure, you'd lose your indexing speed, but if you were clever with how you laid out the filesystem, you might not notice.
Hey, here's an article on some of the F/OSS projects that might help with the bit-lifting: Thanks, Ars Technica!