The release is covered pretty well on the Google Desktop Blog. Features include:
- Improved APIs so that developers can produce more powerful extensions to enhance the functionality of the program.
- Search across computers - allows searching of several computers in a network from one computer.
- Updated preference page.
- Indexing of zip files.
- Advanced search form.
- Playing online games with contacts using the sidebar.
It looks like it's quite a big upgrade, and it needs to be - with much improved searching in Windows Vista, Google Desktop will soon no longer be able to take advantage of the poor searching capabilities in XP. It needs a new unique selling point, which is also unlikely to be the sidebar as that looks set to be a standard feature in Vista as well, with all sorts of interesting widgets. I think they're looking at at least another strong update to the program before the release of Windows Vista in the Autumn. It will certainly be a big challenge for Google.