Well, I participated in my first Yahoo! Hack Day on Thursday & Friday. I'm not sure if I am allowed to tell everyone what my hack was, but I think I can tell you all that I won a trophy for "Best Use of API's". So one month after I started at Yahoo! I get to put a trophy on my desk for Hack Day 8-)
The picture I have attached is the only one I have found that I am in. I am wearing a yellow shirt just to the right of the center.
Update #1: It seems that Chad Dickerson
wrote about my participation in Hack Day here
Update #2: More Hack Day coverage at TechCrunch