[Idea] integration with wikipedia

Hi, I think it might be interesting to have an integration with wikipedia where words found on wiki pages could be highlighted and when the mouse is moved over them, a popup box could open and display the wikipedia information. This integration is done in Trillian IRC and it's quite nice (see attached screenshot). I'm not sure how useful it is though but it's cool nonetheless and shows an example of web service integration (in the loose sense). In order to be performant it would have to be done in a separate thread though and the underlining should probably be done independently of the page's rendering (using javascript). Maybe an idea for a xwiki hackathon? -Vincent