Amidst all the hoopla surrounding the Google Talk launch, one important GMail improvement almost got lost: You are now able to easily use different "From:" and "Reply-to:" fields in the e-mails sent from your GMail account. Just go to "Settings" and click the "Accounts" tab. You can now be email@example.com as easily as firstname.lastname@example.org. (Of course there is rather nifty mechanism in place to prevent fake headers and spamming.)
Also, to sign-up with GMail, new users no longer require personal invites if they live in the U.S. and have text/message capable mobile phone. If this does not apply to you, you are interested in GMail and you still don't have the account (is this even possible?), just drop me an e-mail to email@example.com with the subject "GMail Invite".