ETA for 5.1 JB: no clue! We're going to set pieces of the puzzle together this week. We could have issues... Could be 1 month maybe 2...
I know 1 month seems long, but it's short to work on a project like this when it's a hobby and you've other things to do as well.
Last week, pod2g reported that the Chronic Dev-Team now has all the exploits required to release a userland jailbreak of iOS 5.1; however, it would take some time to put it together into a useable release.