Hi everybody,
This is my first post, however I have been using Paint.NET for many years. I finally feel I have something to contribute. Recently all my associations that use to point to Paint.NET got reversed and set back to Windows Photo Gallery. So I went in to the Set Default Programs in Vista looking for Paint.NET so I could set all the file types to PDN, however I found that an entry doesn't exists for it.
So with a little exploring of MSDN I found this http://msdn.microsoft.com/en-us/library/cc144154(VS.85).aspx which seems indicate that you only need a couple of registry entries to get the Set Default Program UI working.
I would love to see this feature in the future.