What server address do I use to hook up Microsoft Exchange to sync Gmail
Here's Google's support page for setting up Gmail.
http://support.google.com/a/users/bin/answer.py?hl=en&answer=138740
Have you tried to set up the Gmail account via the Gmail tab in the "Mail Contacts Calendars" tab in your Settings app? Just pick the "Gmail" tab (as shown in this picture):
<img src="http://www.ipadforums.net/attachment.php?attachmentid=36096"/>
When you use that tab, it's all ready to go straight to Google/Gmail. You don't have to enter anything but your Gmail address and password.
Maybe give that a try?
Marilyn