A while back I wrote a very simple plugin for WordPress that would automatically insert Dublin Core metadata into the header of my blog posts. I released it under a free license (as version 0.2) with the hope that someone more proficient in WordPress than I would come along and build on my work. And someone did!
Yesterday, I received an email from a Salvatore Vassallo, explaining that he had added two more metadata attributes to my plugin and released the result (as version 0.3). I merged his contributions back into my source code, which I then reorganized and simplified. I released that as version 0.3.1, available as a zipped PHP file.
This is my first real software collaboration, however minor, and I couldn't be happier.