The PSP2 has been rumored for a long time now, but Netherrealm Producer Shaun Himmerick pretty much made the rumors official with the revelation that his team actually have a working PSP2 unit in their office. When asked if we could expect the newly rebooted Mortal Kombat to appear on a handheld system Shaun said;
We’re not launching day one on all consoles like that, we are looking at them; we have a PSP2 in the house and we’re looking at the engine, like what can it support. We’re running at 60 fps, what can we do and do we have to build all the art assets over. We’re definitely looking at them. PSP2 looks like it’s a pretty powerful machine. We don’t have a 3DS system in house yet, but we’re looking to get one, and we’ll certainly look at what its power is.
IGN reached out to Sony for clarification but as expected they refused to comment. As the system is already in the hands of developers its safe to assume that either an official announcement or leak is imminent. I suspect Sony are waiting to see what Nintendo do with the 3DS before making an announcement of their own.