Google Desktop Searching Tool is really great, works good and indexes perfectly all your files, contacts and emails on your PC with a quick retrieval engine.
There's only a problem that I've personally experienced on a machine at work... if used on a shared PC (used by many people, with different accounts), Google Desktop Search retrieves files and emails bypassing the accounts settings. What is the result? you can read all files and (expecially) the emails by other users of the machine. Not too good I think! 
Google Desktop Search is not intended to be used on a shared pc, so be careful...
A little advice to Google... for the next Beta version, maybe you can start thinking to integrate Google Desktop Search with the OS users account (authentication to start using the tool).
Microsoft SQL Server 2005 Express Edition Community Technology Preview (CTP) is out for trying...
For the few people who don't know who is it, it is a free, easy-to-use, lightweight version of Microsoft SQL Server 2005 (born to replace the old MSDE 2000). I don't like to try CTP normally, but this is one of the products that I was waiting for... 