More than the closed tickets and committed code, the face to face time with the other committers is always a plus. Working with someone online is very different than a face to face meeting, and can lay the groundwork for future collaboration efforts.
Jim Keenan drove a workshop at the conference, a new format that provides an extended, freeform timeslot. Jim used the workshop to get everyone there to build both parrot and Rakudo. We were able to get most of the folks there building on their respective platforms. For those who did encounter difficulties, we were able to get some bug reports (and some fixes), and even some patches from those new to the project. (Packy++ and Deven++)
I even got someone potentially interested in partcl (Tcl on Parrot) out of the workshop, a bonus I was not expecting. (Shane++).
Hopefully we can recreate some of this success at YAPC::EU, and definitely next year at YAPC::NA '09. See you then!