As an existing user of both, I’m very excited by this new integration. Key benefits are:

• Your email (which is basically Gmail) is automatically linked to your contact records in Salesforce. No more adding emails manually!
• Your calendar will synch with Salesforce.
• Documents can be stored online with Google, taking care of the expensive excess data storage charges that you get from Salesforce if you exceed your allocation

I’m sure there are many more. I’m very much looking forward to doing a trial of this as I think it could be a wonderful solution for small to medium businesses.
Check out the details on Salesforce.com.