[moomerman]

You just need to sign up for 'Google Apps for Domains' here is the link to the free version (they try and make it difficult to find)

http://www.google.com/apps/intl/en-GB/group/index.html

You'll have to follow the instructions to make changes to your DNS etc.

[tnorthcutt]

Also, be aware that they recently limited the free product to 10 accounts per domain. Likely not an issue for anyone wanting to us @firstnamelastname, but others might find that information useful.