Happy Cinco de Linko!
Today is packed full of celebrations and traveling for me. First of all, it's Cinco de Mayo, which is always a good excuse for a margarita. Secondly, I'm heading to Mountain View to assist my co-workers in celebrating Cinco de Linko. After that, I'm pitching in a LinkedIn softball game trying to beat the #1 team in our league. Then I'll be heading up to the festivities of JavaOne. It's likely I won't be "networking" until late night. I'll be twittering all week if want to know where the good parties are. 
Update: I just learned how to find out when you first joined LinkedIn. Click on "Account & Settings" at the top of any LinkedIn page. On that page, in the upper-right corner in grey text, you should see "User since: " and the date you joined. Interestingly enough, I joined May 27, 2003 - just 22 days after the launch.