We have no schedule, but the current beta framework is very stable and several applications are already shipping with it (eg VDMX, Modul8 very soon). I’d suggest using the packaged SDK version of the framework rather than current SVN, which has some partially implemented additions. Future updates won’t break functionality with the beta.
I’ve added the framework icon to SVN – http://code.google.com/p/syphon-framework/source/browse/ – shout if there’s anything else you need access to.
Keep us posted when you get to release!