On the off chance that this isn't widely known, I'm going to suggest better settings to use with the stock email client when using GMail. The default 'auto' install sets you up with an IMAP connection to Google. You can get better functionality (push notification, folders, contact and calendar sync) by setting GMail up as an exchange account. There's two ways to do this.
First, via the settings menu. Go to Settings -> Accounts & sync and select Add account. Select Corporate. Enter your GMail username (user@gmail.com) and your password. Select 'Send email from this account by default' and then press Next. On the server settings screen, leave everything as is, except the Server value. Change this to 'm.google.com'. Click Next. On the Account options page, set things up as you like. I leave them as default. Click Next. On the last page, give this account a name and press Done.
It's easier if you haven't entered any account in the email client, or if you just delete it before doing this. Launch the email client (the icon in the app folder named 'Email'). Enter your GMail username and password, and then click on 'Manual setup'. For the next screen, type of account, select 'Exchange'. On the next screen, again, all is good here, except change the server name to 'm.google.com'. Click Next, and on the next screen check 'Send email from this account by default'. Click Next, give the account a name and then click Done.
I haven't had a lot of time to play with this, but it seems to work well. YMMV of course.
A co-worker of mine turned me on to this as a way he set up push GMail to his iphone. He got the info from this URL;
http://www.google.com/support/mobile...?answer=138740
One of the neat things about setting the account up this way is that the stock calendar app can now see your google calendar.
Hope that this is helpful to others.
Rick