@pyrochild
hey would make more sense to write a WIC aka Windows Imaging Component plugin for paint.net
http://msdn.microsoft.com/en-us/library/ee719654(v=vs.85).aspx
http://code.google.com/speed/webp/docs/webp_codec.html
this also has a huge benefit of allow for opening RAW files like Nikons .NEF and Canons .CR2 and any other wic codec from sony, panasonic, samsung etc,
i posted about this a while ago