I saw this on the Official Google Blog tonight: A smooth Apps move:
Today, it becomes a lot easier for organizations and schools to start using Google Apps email services without leaving any of their valuable email data behind. Our new self-service mail migration tools enables administrators using the Premier and Education Editions to easily copy existing mail from an IMAP server over to Google Apps. Now businesses and schools can spend less time worrying about "maintaining infrastructure" and focus more on the things that matter most to them -- like healthcare or educating students.
One of the first organizations to test this out, Central Piedmont Community College, replaced its old email system for 30,000 users in just 3 weeks. And that process came down to 3 million emails flying from their server over to ours in just 24 hours -- more than 2,000 emails per minute, all without missing a beat.
So what's the downside? Seems to me like moving to Google would be a no-brainer. Why would anyone spend their time and money maintaining e-mail servers when you can get Google to do it for you? Surely we have more important things to worry about than maintaining e-mail servers, spam filters, etc? What am I missing?