Well if you jailbroke it with blackra1n, in cydia add the source blackra1n.com, then install blacksn0w, and it should work...
How Do I Unlock My 3rd Gen Ipod Touch?
Crap this is an old question. Ipod 3g hasnt been realeased yet? 0.o
I'm from the futttttuuuuurrrreeeeeee
I'm from the futttttuuuuurrrreeeeeee