Currently Google Desktop Search scans the following types of items:
- Outlook / Outlook Express email messages
- AOL Instant Messenger conversations
- Internet Explorer pages (it caches pages you have visited)
- Text files
- Word documents
- Excel spreadsheets
- Powerpoint files
I've just now installed it and the index is currently building. I'll provide more info after i've been able to play with it for a while but so far i'm very impressed. Getting the instant results of a search of my Outlook email is amazing.
Here are some more links...
Get the download
The About and FAQ page