Sources have confirmed to BetaNews that Facebook will be launching a multi-platform instant messaging service built into a user's profile page.

Based upon the open source Jabber platform, the IM service will be Web-based only, as Facebook doesn't currently have any software client developers, one source said. Blog TechCrunch, which first reported the news, says the IM service could be rolled out to the public next week, but our source wasn't given a specific date.

Such functionality has already been adopted by Google with its ownGtalk service, which has a Web-based component that resides in a user's Gmail account. Other Web-based IM services like Meebo have seen moderate success due to their portability, but software clients still rule the industry.

MySpace attempted break into the market with its own software IM client linked to user profiles that integrated voice-chat features. However, adoption of the client has been minimal, as AOL, Microsoft and Yahoo remain dominant.

It's unlikely that Facebook's Web-based IM service will be attractive to anyone other than devoted Facebook users, but the feature is important as it provides another reason for users to stay on the site. Although Facebook is one of the leading destinations on the Internet, it's user base doesn't tend to stick around for long periods unless they are looking at photos, which negatively impacts advertising -- the site's only current revenue model.