46 named contributors. The vast majority of them alumni.
Given that we've got about 300 alumni, and that we were given 20 hours' notice late on a weekday evening, I'm rather pleased. There were a number of folks who didn't make the feedback-submission cutoff deadline but sent in "hey, I'm sorry I just read this email and didn't make it in time, but good luck!" notes, and probably more people who helped in than we were able to identify (most folks didn't sign in when editing the wiki and left IP addresses instead).
A little tired now - not physically or mentally, but people-buffer-wise; I've spent the last couple of days stirring up and sustaining multiple whirlwinds at once, and I'm actually looking forward to a day of solo output now. (This is relatively rare.) So tomorrow I will be working through my work backlog of things I was going to do in the past two evenings before Olin stuff ate my life. I'm done with that now - just in time for a whirlwind week in Rochester and Toronto hanging out with various open-source-and-education colleagues. Sweetness.
 Olin has graduated 4 classes ever (I'm part of class #2). On average, each class has 75 members.