I've been following Parse for a while now, and I agree with technogarden. Their platform is impressive, and they're adding useful new features at a rapid rate.

It would definitely be cool if they open-sourced the platform, but, in the meantime, you might be interested in this project:

http://code.google.com/p/openmobster/wiki/learnmore

Personally, though, I don't mind paying for a service like Parse. If someone is willing to not only build the features I need but also to wear a pager and get up at 3am just to keep my users happy, I'm more than happy to give them some of my money.