Now that we have our iPhones I wanted to find a solution for both my wife and I to sync our data from our Google Apps domain to our phones. Ideally, I would have liked our phones to sync directly to Google, but that is not available, so I needed something to work on my wifes Macbook Pro and my linux laptop.
For my wife, we are using Spanning Sync to sync Google Calendar to iCal. Then we sync her iCal and Address Book to Mobile Me (or actually .Mac, since we are still running 10.4.x). Then her iPhone syncs with Mobile Me wirelessly. This allows her to modify her calendar on her iPhone, or her Mac. Also she can use either Google Calendar or Mobile Me to modify or view the calendars on the web.
For me, I don't have my ideal solution. I am using Google Calendar for my calendar, but since there isn't a solution on that will run on linux that will sync to Mobile Me, and am just using the web interface to the calendar on the phone. For contacts, I manually imported my contacts to Mobile Me, and then just sync directly to my phone.
Ideally, I will have a solution for my calendar, that would allow me to use the phone's calendar application. Since I doubt that Apple will allow syncing directly to Google, I think that answer is either: