A few weeks ago we took a "leap of faith" and signed up for Google Apps Premier Edition. It was really just the logical next step as we all used gmail privatly and Google docs heavily at work to create and share info.
Setup was pretty straight forward except mail migration. Our previous mail provider Sysedata did not have any relevant data available, but after mailing customer support I found that their servers was running something that resembled Courier-IMAP. Combined with a quick search I pieced together this setup that worked flawlessly when migrating all our acounts over to Google Apps: