I had a BlackJack1, then a Blackjack2 both windows mobile phones. I used quite a few 3rd party windows mobile apps to make the phone work how I wanted it when I had my own Exchange 2007 server. Call Firewall, Windows Live, Yahoo, Google Maps (with latittude). 

A few months ago I retired my Exchange 2007 server and moved my domain's email to google's free hosted apps service

My next task was to make my phone work with google's service just like exchange. I got it to connect but wasn't pleased with the functions or interface. Then last week Google released active sync. So I went out and got an iPhone. I provided my username and password and it downloaded my contacts and one calendar. As expected I attached to Google's servers via IMAP for email.  Then, after some research I was able to sync all 5 of my calendars, including one of the wife's. 

And the best part is all the calendars are in different colors.

Likes: Calendar with Google's multiple calendars, photos, camera (much better than BJ2, maps, Tweetie (AMAZING).  Google's reader site looks great on the iPhone.

Dislikes: You can't seem to move an event between calnedars neither from safari nor the iPhone calendar app.

Some App's I'm Using: Public Radio, Facebook, BeejiveIM, Tweetie, OrbLIVE, TWC, Urbanspoon, FreeWi-Fi, Wordpress, Pandora, Flixster, and Yelp.