Read this on some other message board and it worked perfectly, thought I'd pass it along:
You can not use the gmail quick setup on the iphone with domain email.
When you add the account, choose "Other"
Click POP tab and enter as follows, customize what is in the [ ]
+Account Info+
Name- [name]
Address- [[email address]]
Description- [description]
Incoming
Host Name- pop.gmail.com
User Name- recent:[[email address]] (add the recent if you are also
accessing this account with another POP client, ie outlook, apple
mail, thunderbird. If you only access this account via webmail, you
may omit the recent: )
Password- [password]
Outgoing
Host Name- smtp.gmail.com:587 (I don't know if 587 is a must, but it
works!)
User Name- [[email address]]
Password- [password]