The Yufi hacker dude™ is back with another blog post and this time he asks for your help. The goal is to create an open Vita SDK. He says that the reason why no free SDK exists yet is that there are people with knowledge how to create one, but lack time to do so and there are people who have time but lack knowledge of the Vita's internals. So he created an awesome pdf document describing what's needed for an open toolchain and how Vita's executable format works. You can check out his full post here.
Yifan Lu said:P.S (in an unrelated subject): Did you get a PSM license? If not, don’t fret, we got you covered. Just make sure you have the developer assistant installed on your Vita.