Pushing beyond its mobile Skype service, iSkoot has purchased social.im, and instant messaging client that let’s you IM all of your Facebook friends. iSkoot already has a partnership with Skype to bring the VoIP service to mobile phones, including Skype-branded mobile phones in other countries. With social.im, it will add a Web-based IM service that taps into your social network.

Social.im was a promising service, until Facebook launched its own IM feature. The play here for iSkoot is to bring that social IM functionality to its mobile client (as well as news and other information).

Terms of the deal are not being disclosed. iSkoot has raised $13 million from investors including Khosla ventures and Charles River Ventures.