I know I am just the latest one reporting on this, but I will add a small twist. If you are using Gmail as the outgoing mail server in your client configuration, what this means is that Gmail won’t rewrite your From address anymore. As I’m using at least three different accounts when sending out mail, depending on who I’m sending it to, what’s in it for me is that I can now use Gmail as my only outgoing server, not having to fight with corporate SMTP gateways that insist on me having a fixed IP address or such. Even my cellphone is now configured to send mail out via Gmail.
What this also means, however, is that more and more of my life is tied to Google.

