I think someone should come up with grips like this that contain batteries in the grips :P. That way you have longer play plus make it more comfortable to hold :p. (although weight and balancing may be an issue.)
@iamkoza: No way, the problem is the locking part of the grip sits right under the Vita's power input; you'd have to remove it making the grip useless or unable to hold your Vita securely.
@Papa Elf: there is a Vita power grip made by Nyko technologies http://nyko.com/products/product-detail/?name=Power+Grip+for+PS+Vita , but it's not out yet. I've been waiting for it for a while. It looks amazing and the price can't be beat.