Interesting, but pretty sparse on information ... what exactly does zStack offer that's unique and helpful for mobile apps?

See also http://www.stackmob.com

At first I thought they were in deep trouble with this hitting the front page mere hours after the iCloud announcement. Then I looked at what the actually offer, and it looks like they will be able to compete. They have social, notifications, cross-platform-ness, and analytics in addition to just storage sync. Good luck, I may become a user!

Looks really good in principle, although I think they're offering too much for a first version. The app backend alone is compelling enough for v1.0 IMO.