Gmail has secure web access, mail filters (automatic sorting of incoming mail into labels/folders), and killer searching. Mobileme doesn't. However, gmail has problems importing contacts.
I'm currently using gmail for mail, but MM for contacts and calendars. I'm using gmail's filters to automatically forward some gmail to MM, to use the push feature as a "check email" alarm. This way, I get the best of both worlds:
- I get gmail's secure web access, mail filters, and killer searching.
- I'm only notified of "important" mail messages, and not all of them. Not only do I get fewer interruptions, but I get better battery life.
- I can backup my contacts.
- I don't have to give out a new email address. I'm still in the MM trial, and I haven't decided if MM is worth it (as opposed to buying a more expensive MM-like service).
Basically, gmail is used for all mail, and I just ignore and periodically delete all MM mail.