Google announced Google Mail is becoming Gmail in the UK in May. Then some day I decided to swap over my Google Account primary email address from @googlemail.com to @gmail.com. Everything continues to work as before. It should be working because I assume googlemail.com or gmail.com is alias to the other.
After quite a long time (at least 2 weeks), I noticed Google Contacts stopped synchronisation from 28 May, 2008. Because Google Mail and Google Calendar continued to work all right, so I did not think it was problem of my Google Account change. I did not regard the domain name swap was a change. I thought it was merely Google was updating Google Contacts programme or server something.
I have been waiting for Google Contacts synchronisation back to normal for a month. During the month I googled quite often if someone else encountered the same problem, but I did not find a case like mine.
I could not live up with a situation that I had to enter a new contact twice any longer, so I started investigating harder. And only by change I realised it might be a problem caused by domain name swap. Then how to change Google Account information stored on my Android? I find it is not straight forward.
First there is no interface for change the Google Account on Android. Someone mentioned a tricky method by changing the Google Account password then reboot Android. But it did not work on my Android G1. After reboot, it only pop up a box to enter password, not for account username.
I manage to change Google Account by clicking Setup -> Applications -> Manage applications -> Google Apps -> Clear data, then reboot. Clear Google Apps data clear all contacts on Android as well, but it is not a problem for me because I have all contacts in google cloud anyway.
A by-product of my investigation is I find Android support Google Apps Account as normal Google Account, which makes me very happy because I use Google Apps Account much more than Google Account.