Despite the fact that NGP was starting to grow on us, we knew it was a temporary monicker, and whether or not the NGP is called PS Vita or not, we can be sure we'll probably find out the NGP's proper name come E3.
But let's review the supporting evidence, collated by VG247.
- Domain registrations were put through for PlayStationVita.com and PSVita.com. - This blog stated that the NGP would now, in fact be called PS Vita - Ripten apparently has a source stating similar things, plus that the new Uncharted game is called Uncharted: Golden Abyss.
That being said this has to be treated as a rumour until now. We won't know for sure until E3.