Congrats to Andy, Gordon, and Leonard, and about damn time. I first saw Upcoming almost exactly two years ago and thought “Wow, now that is how to do calendaring.” (and apparently I was jealous even back then!) Good luck!
Now we can all speculate on what calendar.google.com will be, but I’m thinking this round might be going to Yahoo.
update2: Flickr, Upcoming, and Ning, all built on PHP.