Just a quick note to let you know that Gmail has been having problems with their RSS feeds, which power the Gmail inbox previews on Protopage.
Until Google fix this problem, there is a workaround. Google will allow you to access your Gmail via POP3 - and you can enable this feature by logging into your Gmail account and clicking the Settings button in the top right of the screen. Then select the Forwarding and POP tab, and in the POP Download section choose Enable POP only for mail that arrives from now on. Then click the Save Changes button.
Now, add an inbox preview widget to your Protopage, and click the edit button. For inbox type, choose POP3 (instead of Gmail), and enter your login and password (for login, if you Gmail email is email@example.com, then just enter yourname as the login).
For the POP3 server address enter pop.gmail.com and tick the Server uses SSL box. Finally, enter http://mail.google.com/mail/ for the Webmail URL, click Save changes, and voila!
UPDATE: Gmail have restored their RSS feed service, so this workaround is no longer necessary.