It was just added support to uuid datatype in cvs head. This type will be available in next Postgresql release 8.3. Thanks to David Bachmann for his patch! You can get more info about this patch in this mailing list post.
Also was added support for copy in and copy out operations. Now, users can provide streams which can be copied directly to and from Postgresql tables! Thanks to Kalle Hallivuori for providing a patch! Thanks to Truviso for giving support to Kalle. More info about that including a demo and ready to use compiled Npgsql.dll versions can be found here.
That's it! As soon as we get more features added, I will post info about them here. Stay tuned! :)