You get an "atta boy" if you know what DKIM stands for.
DKIM - DomainKeys Identified Mail. This is a technique for signing outgoing e-mail messages so sent mail is less likely to get caught up in recipients’ spam filters.
Google has added this to all Google Apps users. Administrators can enable DKIM signing in the “Advanced Tools” tab of their control panel.
Once you get this text string, you have to go create a TXT record in your DNS.
Here's what mine looks like:
It took 20-30 minutes for the DNS updates to propagate.
There's a nice tutorial here.
Nice job Google! And the price is right: FREE.