I have to do an impromptu additional blog post because I just found out that my first big open source project, Apache FOP, just had its 1.0 release today.
I started FOP in 1998 and, in 1999, donated it to the Apache Software Foundation. I haven't been involved in its development for a long time but am delighted to see it reach 1.0, and from the articles written about its release, it sounds like it's actually used by a lot of well-known companies.
FOP was the first project I used Python on. It was the first open source project I did involving other contributors. It was the first large Java project I did (and I remember first grokking things like the Visitor Pattern in trying to solve design problems in FOP)
For a blast down memory lane, be sure to look at my archive of the old FOP website.