Software. An exploit will most likely be available after a few months; as it's completely new hardware and software, it'll take much longer to unlock than, say, the latest android phone. If you absolutely hate AT&T and have to get a Vita 3G, you might want to look into importing yourself a Hong Kong/Singapore model and a turbo sim. Just be aware that importing a Vita costs about seventy dollars more than a yacht.
I would say that there is something that will come up. I have two on order and am waiting for them to come. I have bought the 3g model and i don't have ATT. So i do hope that something come so out. Plus there is no ATT around me so it would be hard to hook it up.