(Crosspost -- let's discuss this at the General Developer Forum thread http://moodle.org/mod/forum/discuss.php?d=41243 )
I am now finishing the first stage of merging the MULTI_ENROL branch into HEAD. I will be re-testing everything (some minor breakage is expected initially) before I call it a day.
This branch was mostly the work of Patrick Li (thanks!) -- but the commit messages don't credit that correctly. I'll fix my merging scripts ASAP to give credit where it belongs.
I also intend to merge all the patches and new plugins on top of Patrick's work. Ping me if there's something I've missed (specially if you don't have direct access, though I'll arrange with MartinD to grant access to new plugins to their authors).
Sweaty hands now... let's retest everything again...