The first fix is free

Google launched Google Apps Team Edition.

In a nutshell, users of an organization can setup a Team, with all the goodies of Google Apps for Domains, using only a valid email address. no need to bother the IT administrator...

Smart, very smart. Get the users addicted, and have them push for the stuff internally, a "upgrade" to the bussiness package (watch the video at the Google Talkabout blog, and pay close attention to the last 30", starting at 1:54").

My concern is the Google Talk integration. You can use the Google Talk server with those email addresses, but you'll loose XMPP federation, because the required SRV records will not point to the Google Talk servers.

Also, I wonder what happens if a @example.com user starts using this. Now that one user @example.com is using the GTalk network, will internal routing of the GTalk network assume that the entire domain is local or this per address? So if a user with an email address @simplicidade.org uses this, will it sink all connectivity between my domain and the Google Talk network?

This needs to be checked further...

(thanks to fabieuse for pointing this out in the comments, even if I didn't get all the implications at first)