A growing number of third party software has already included
wikipedia data somehow. It starts with trillian, there is a wikipedia
widget for MacOS X and one company with friendly relations to
Wikimedia (
Answers.com) has released a tool. Not to forget Babylon.
One tool with is missing support for wikipedia data is currently
Google Desktop. Version 4 was released hours ago and the company is
trying to catch up in terms of the number of gadgets offered by
announcing a contest for creating these. Details can befound at
http://desktop.google.com/contest.html. There is also an IDE for
development at
http://desktop.google.com/designer.html a documentation
for the SDK at
http://desktop.google.com/developer.html.
Maybe someone is interested in this challenge.