An interesting perspective; see the full post for more details
Though we may not be sure about his prediction that Google will act before Firefox, we think Forrester's Jeremiah Owyang offers a very compelling vision of the future of browsers and social networks in his excellent report The Future of the Social Web."... in a bid to extend the reach of its new browser, Chrome, we expect Google to build OpenID and its associated friend connections into the browser; look for Firefox and eventually Internet Explorer to copy this feature. Facebook and MySpace will also likely build a way for users to surf the Web within the Facebook experience, retaining the social functionality. These connections won't be perfect, but they'll allow social networks to colonize communities and other parts of the Web, extending their experience out to other sites through the shared ID. As a result, in two years, portable identities will become a ubiquitous part of the online experience as they reach maturity."
It's only logical to extrapolate from that analysis that the line between browsers and social networks will become much less clear and the two types of software will very likely compete with each other.