They're got an Alpha program going (which will set you back $799) and according to the FAQ, it won't be publicly available until November (and will then cost $999).
revMobile will be the fastest way to develop mobile applications. it will be a cross-device product, so you will be able to use the same code to deploy to multiple mobile platforms, while still providing a native experience on each device.
The article "revMobile for the iPhone: the pre-alpha is here!" provides an overview of working with revMobile, taking you through implementing multitouch support in an application.