Using Google Talk with a non-GMail address
Or, Google Talk considered evil. Well, not fully evil, but it has one evil feature that people keep reporting bugs about.
Short answer: No. Just use your GMail address. Long answer:
As many of you probably know, it's possible to add non-Google e-mail addresses to your Google account. Seems reasonable. Less reasonable is, it lets you use this address in Google Talk. Previously only in the web-based chat applet, now apparently also in the Win32 client and Pidgin.
This can't really work in the XMPP network though. You're using an e-mail address that is not connected to GMail or Google Apps in any way on the XMPP network. How can someone on a non-Google Jabber/XMPP server reach you? "firstname.lastname@example.org is talking to me but doe.com is not running a Jabber server. Go away, you don't exist!"
To get to the point, what seems to be happening under the hood now is the following. When you try to log in to GTalk using the Win32 GTalk client with your email@example.com address, the client will send a special flag during log in. Without that flag (BitlBee doesn't send it), it will refuse your login. If you do send it, the server will let you log in, but also tell you "By the way, you're not firstname.lastname@example.org but email@example.com."
Also, your contacts will only see firstname.lastname@example.org in messages you send them, and in their contact list. So really, there's no point. Just log in as email@example.com.
If you have no GMail address attached to your Google account, this trick won't work. Not with BitlBee, nor with any other client. Please either get a real Jabber account (on your own server or on any of the existing public ones) or a GMail account.
But my friend/cousin/neighbour/hairdresser says he can log in using his firstname.lastname@example.org account!
That's because he has a Google Apps for your domain account. That way, the whole domain (e-mail, XMPP, etc.) is hosted by Google.