^ iOS5 Beta 4 is out but for Developers only.
If you know someone with a dev account you can get them to add your phone's UDID and then u can use it.
Google around, there were people doing it for just about anyone.
I'm on iOS5 right now. I miss my jailbreak though

. But it sure is awesome!
I notice I get a lot of crashes when I'm playing sf4volt