The current "community" of devs and people that actually have an apparent working Jailbreak for 3.1.3 will not release it, for whatever reasons they think are appropriate. Of course, it smacks of more elitism unfortunately - "Hey, look what we've got, and here's a video to show it off, but don't you dare ask us to release it 'cause that's not gonna make it happen any faster."
Kinda childish crap, really. If they had/have it, they should shut up about it or put it out, not do the bragging stuff...
Apparently they all agree not to release anything till probably firmware 4.0 is out later this year with the new iPhones. Personally I find it reprehensible but, that's what you get with the egos most of those devs and hackers have.
Comes with the territory I suppose. Nothing new to see here, move along...
MB models are 2nd gen; third generation models are MC, with the exception of the 8GB iPod touch because there is no 3rd generation model. It's the 2nd gen with a new bootrom so it gets called the MC model but it's still exactly the same hardware as the 2nd generation, there is nothing new but new bootcode, that's it.