And so the Google Contacts, Google Calendar and Google Mail integration with Sage ACT! 2012 had no issues woriking against the @sagedemos.com domain I setup and configured for Google Apps.
This was great, becasue I really like to use Google for mail and it's very convenient to use Google Talk integrated with my contacts when I'm on the road, but I hated having my business e-mails come from an @gmail.com domain.
One of the most common questions I get related to the Google Integration with ACT! is; how can I limit my users to what (if any contacts) I want to allow them to sync to Google. This one is easy - because if you log into ACT! as a manage or admin user you have an option to manage sync sets that are available to standard users in ACT!. The sync sets can be available to all users or only to specific users, so I can ginve Suzanne access to integrate all of her customers, but limit Brandon to only contacts marked private, and Paul doesn't get any sync sets so he can't send any contacts out of Sage ACT! to Google (this is also available in Outlook contact sync).
In the majority of cases the Google Integration with Sage ACT! is setup and go, but in one of the offices I work out of they use a pretty restrictive network setup which doesn't allow the e-mail integration from Google. It takes a little tinkering, but you can setup the Google integration to use a proxy server which let's me get my e-mails recorded to history even when I'm on the locked down domain.