Yesterday, Bebo announced that it will team up with Microsoft on a new instant messaging initiative that would allow its users to use Windows Live instant messaging on the social networking site.

The Bebo-branded IM will have restrictions on who can contact whom, however. Consistent with a tendency for social-networking sites to build "walled" communities, users will not be able to send instant messages to Windows Live Messenger users who do not have Bebo accounts, and Windows Live Messenger users will not be able to see if their buddies are logged on to the social networking site. Bebo users who use Windows Messenger can add an "IM Me" icon to their profile page, which will allow them to begin IM conversations with a single click.

This marks the first time Microsoft has partnered on a communications service with a social networking site. Rival MySpace has also launched its instant messaging service earlier this year, but has kept it separate from other IM clients.