i don't know if now fw 2.1 unlocks 1gen iphones as well, but this is what happened to me.
after updated my 3g iphone to fw 2.1, (cuz im bored!) i plunged my jb 1gen iphone and updated it to fw 2.1. guess what!??
it just WORKS!!!! i mean no activation or jb is needed!!! 😀