I enjoyed "The Five Stages of Hosting" posted earlier (http://news.ycombinator.com/item?id=3526767). In that metaphor, Google Apps is the large, modern and comfortable house in a central location with most amenities and virtually rent free - only downside is that the landlord won't let you knock down the walls, and there's no way a grand piano will fit through the front door.
Also Google Apps broke on me and their support is absolutely utterly useless.
And when something gets blacklisted, TSHTF. It's much easier to sort it out yourself.
Actually, the Google Docs integration is probably the biggie.
Re: Calendar I've done two calendar technology migrations for 500+ person companies - they are typically forklift upgrades done over a weekend. You basically lock in your resources (rooms, typically) a week ahead of time, have people rebook any forward meetings into those resources - and have everyone switch into the new system on Monday. As long as people have the right client (in Googles case, that would be a "Web Browser") there is no lock-in.
I could take a 500 person company from Google Calendar, Email, and Contacts over to Microsoft exchange with a team of three people in under a month, with maybe 2 days of disarray (monday) as people (who ignore instructions the previous week) update the mail servers and LDAP servers on their various Androids, iPhones, Macintoshes, etc...
Just make sure you keep your primary directory in your own LDAP server, and you will be good to go. Don't outsource the directory. And stick to something LDAP compatible.
Then again, the user experience with the leading alternative solution (MS Exchange) is so miserable that at one organization I'm aware of, the public announcement of a migration to Google Apps for Domains was greeted with a standing ovation.
Another interesting factoid: Hal Varian, co-author of Information Rules, which largely discusses strategic use of lock-in by both vendors and users, is Google's chief economist. I suspect this is a subject the organization understands well: http://www.amazon.com/Information-Rules-Strategic-Network-Ec... http://en.wikipedia.org/wiki/Hal_Varian
I disagree with the metaphor of the landlord reading your mail: As slightly worrisome as it is, having a person and an algorithm read your mail is not comparable. Of course, the risk is that the results of the analysis is leaked outside the algorithm.
I have taken a conscious decision that I don't care about this risk. I'm putting my money (yes, it's a bet) on Google being able to profit better from advertising to me without violating my privacy. It's a "life's too short" trade-off.
http://www.zulius.com/how-to/set-up-postfix-with-a-remote-sm...