Windows Desktop Search, which is installed with MSN Search Toolbar, will
find anything on your computer ; e-mail messages, calendar appointments,
photos, documents, and more. Searching your computer is as fast and easy as
searching the Web, and the Desktop Search results window includes rich Windows
Explorer features, such as multi-select, right-click, and drag-and-drop
functionality.

Windows Desktop Search can be extended to index the contents of new file
types and data sources. The user interface can be extended by associating
icons and context-menu handlers with those items.

Also, queries can be passed into the Windows Desktop Search application and
returned so that other applications can display the result sets from within
the application.

This
document explains these beta extensibility options and their
implementation.

The first things that pop-up was Groove.
It would be really great to be able to search accross all groove workspaces to
find documents, discussions entries, pictures… I think that Groove would be a fantastic new data
source.

The only problem is that you need to implement the data source in C++, back
to the roots.