I read occasionally about folks' emails vanishing, and it made me
think...

Q: Has anyone an idea as to the best way to backup Gmail (and even
other Google services utilizing the shared storage, which I purchased
more of)?

I once connected via POP and "caught up" with an Outlook client, but
this isn't a real backup. It is more like a copy, as it is [probably?]
not usable as a "restore" mechanism.

Q: So how would/could one backup their Google stuff in such a way that
it could be restored in the event of a problem?

What if...

Q: Is there a way to either pay for backups/restores via Google?

Q: Failing in that, is there an API that would allow local "full"
backups (via webDAV, etc.) and subsequent "incremental" backups
utilizing our client software?

The base requirement, and pretty much deal-breaker, is whether the
solution allows seamless restores, preferably without any Google
(human) effort required.

Ideas?

TIA!

Google already keeps backups of your mail. Any additional backup that
they would do wouldn't be any help since, should your account ever be
compromised, the attacker could just delete all the backups.

You've already identified the best way to do backups: download
everything with a POP client. It is true that this isn't a "full"
backup in the sense that you'll lose your labels, but at least you've
got all the email. (You can backup with an IMAP client to preserve the
labels, but it is tricky to make sure the client actually grabs the
full content. And there is a bigger danger of losing all your email if
you reconnect with your IMAP client to an empty account.) POP will do
"incremental" backups, in the sense that it will only download the new
mail since the last download. In addition, you can backup your
contacts manually by exporting a csv file.

Here are the instructions from google:
http://mail.google.com/support/bin/answer.py?hl=en&answer=34030