UMS = Usb Mass Storage
The option is there in Settings, and the code for it's ability has been merged in CM's source, but since it wasn't working right, i removed it until it was fixed. Now Harsh's kernel supports it, it just requires support on the rom side of things. I'm still working on putting it in and making sure its working properly. That and the internal storage toggle are the two main things on my list. I may put out beta4 either tomorrow or wednesday, that build has lots of internal fixes, that should hold you guys over until next week, when i get back to work on it.