Hotmail may have three times as many users as Twitter, but it's looking for something that may not be as easily quantifiable - the cool factor of  Google's Gmail. That's something that Microsoft has been working on for a while now, with a full redesign of its email client last year.

Today, the company announced that it's adding another bit of cool to its 350 million member email system - full chatting capabilities with Facebook's 600 million member network worldwide.

Microsoft first announced Facebook chat in Hotmail as a part of a number of updates last September, but the feature was only activated in the U.S., U.K., France, Brazil, Germany, and Russia. Today, the company announced that it would be available worldwide, wherever both Hotmail and Facebook were accessible. Hotmail program manager Dick Craddock the company's little brother syndrome when it comes to Gmail in the announcement.

"While Gmail beat us to bringing their own chat into the inbox," writes Craddock, "we have now gone a step further and brought both our own chat and Facebook chat into your inbox."

Take that Gmail.

Being serious, though, most integrations like this have one exciting thing in common - they're good for the end-user. The feature lets users on both ends - those logged into Facebook and those on Hotmail - communicate seamlessly with each other. Gmail only has Gtalk and no Facebook.

According to Craddock, the response to the feature has been good since it was first announced last September.

"Since announcing the availability of Facebook chat in Messenger worldwide two weeks ago, nearly 2.5 more million people connected their Facebook accounts to Windows Live, bringing the total to over 20 million customers," writes Craddock. "And with three out of four Hotmail customers using Facebook, we expect that many more people will want to take advantage of this feature, now that it's available from your Hotmail inbox."

If  you're a Hotmail user and haven't yet tried out the feature, all you need to do is connect your Facebook account to Windows Live and check the box for "Chat with my Facebook friends in Messenger."