Carriers are increasingly investing in startups in an effort to differentiate their services, and social networks are the primary focal point for them and other players in the mobile ecosystem. So it’s no surprise that mobile software powerhouse Myriad Group has acquired Xumii, a 17-employee outfit that makes a next-generation address book for cell phones.

The Xumii product integrates social networks, instant messaging and media sites, and allows users to access them with a single sign-on. Xumii — which was acquired for an undisclosed sum — has raised $5.3 million in funding and supports a smattering of feature phones and smartphones from AT&T and Verizon. It faces a ton of competition from others looking to integrate social networks on the phone, but as the inexpensive and social network-focused handsets from INQ Mobile have shown, there’s plenty of opportunity for manufacturers that can build a messaging-friendly handset with real social-network integration. And Myriad, which provides software to key manufacturers and more than 30 operators, could be a massive distribution channel. (Image courtesy of Xumii)