Recently, Google announced that they now support email over ActiveSync. So in theory you could set the phone to get email, calendar and contacts via ActiveSync and not use IMAP for email.
I tried setting this up, but found the email part of ActiveSync to be unreliable (at least with my “Google apps for your domain” account) – it complained about keys and lost the email from the phone’s inbox.
To be fair, they’re targeting the ActiveSync support at the iPhone and Windows Mobile, not Android.
Perhaps reliability will improve when the system has been running a bit longer, it would be nice not to have to use IMAP and ActiveSync to access the second Google account.