The latest stable version of Yahoo! Messenger is v. 10, which unfortunately doesn’t let you chat with your Facebook friends. For that reason we are not going to focus on Yahoo! Messenger 10, we are going to focus on Yahoo! Messenger 11, which is in Beta. As a matter of fact, people keeping track of these things, will point out the fact that Yahoo! Messenger 11 Beta was rolled out to the public back in November 2010 – that would be more than 3 months ago.

If you get Yahoo! Messenger 11 (you can grab it straight from Yahoo! here) and link your Yahoo! account with your Facebook account (which is a very simple process; learn more about it here), you will be able to talk with your Facebook friends from within Yahoo! Messenger.

After you log into your Yahoo! Messenger account, down at the bottom of your list of friends you will see a Facebook Friends entry. Next to if you will see a “Sign In” button. Click it and you will sign into Facebook Chat. You can then see which of your friends are on Facebook Chat and you can talk to them from within Yahoo! Messenger.

The fact that you can chat with your Facebook chat is quite nice all on its own. What’s even nicer is that you can keep the Facebook chat going after you log out of the desktop version of Yahoo! Messenger 11 Beta. You can keep the chat going via SMS by simply registering your mobile device (check out this article if you need help registering it).

Register your mobile device and when you log out of Yahoo! Messenger for desktop, you will be automatically logged into your mobile device. If a Facebook friend sends you a chat message, that message will be forwarded to your mobile device as an SMS. When you reply to the SMS, your message will be sent to your Facebook friend. It couldn’t be any simpler than that.