Yep, something similar happened to me - I released what is now https://github.com/punker76/gong-wpf-dragdrop on google code in 2009 (I think) then pretty much lost interest. Forward on a few years and @punker76 had uploaded it to github, and continued working on it. It was a strange feeling when I first became aware of the fork - like seeing an inanimate object come to life.
