Until now, releasing the port was either painful (because I had botched the 1.x port) or not very useful (because newer versions of Paint.NET depended on 2.x features that we were missing). In Mono 1.2.4 we finally have an implementation of the *Strip classes that are heavily used in Paint.NET for the menus, toolbars and floating editing gadgets so now Paint.NET looks great.
The port is not complete, but it works. Am releasing it to the public since so many people asked about it and volunteered to contribute to complete the port.
Feel free to join the effort.