There is only one file type that uses the .WP3 extension:
Microsoft Photo Story Project File
Project file created by Photo Story, a program used for creating digital slideshows; contains pictures, effects, captions, audio, and playback settings; used to compile personal photos together for playback in desktop and mobile device video players.
WP3 files may be exported to .WMV files in Photo Story.
|Microsoft Photo Story||Free|
Updated: May 12, 2010