I'd say it's an open question. It depends on the hardware manufacturers and carriers and what they let you do, and at this point it's anyone's guess as to what will be allowed where. Initially we probably won't see "anything goes" types of deals, but maybe we will later on. Once you get sources though... I don't think it'll be long before people start doing C-based stuff. The Java environment (which isn't really Java in terms of the VM) is so that they can keep some semblance of control for non-hacker type people.