I hope that the RAM isn't encrypted, logically, it wouldn't, as that would use precious battery and cpu cycles that wouldn't be an issue a console. But then again, it is freedom fearing Sony.
Let's assume isn't encrypted. That means someone needs to do a hardware RAM dump in the worse case. I don't want to sound like I have any authority, but I think our top priority should be doing this as most exploits will be untestable and unusable without knowing where the stack is and how to get to the framebuffer and etc.
Now another option is somehow getting unsigned code to run that is not a buffer overflow exploit (I would think this is harder as you have to somehow get the device to load a binary willingly. Is it too much to wish for a hidden debug mode? Maybe someone can get their hands on an official devkit and use debugging features to find memory layout?).
Another option might be to look for jtag (or similar) debug ports. The vita uses proprietary soc but uses the cortex a9 cpu. IMO, this might be just as hard as dumping the memory.
Now people with more knowledge should correct me if I'm wrong, but most if not all the "first" console hack required a hardware hack of some sort right? Because only after extracting system software and/or hardware information can the developers work on "user level" exploits.
Oh, and I guess I'm Asking this because there is a chance I found a buffer overflow in vita code. However before you get your hopes up, some other explanations for the system freeze that I found could be because of a bad error handling, an intended protection mechanism, or just an unexploitable bug. The only reason I even suspect stack overflow is because it involved large inputs.