LinkedIn and Facebook on collision course?

I signed up for LinkedIn in mid-2003, and since then I have not been very active on the service other than accepting invites as they came to my inbox.  Over the last couple of weeks, I have noticed a significant increase in the number of requests from friends and colleagues and interestingly most of them are not from the technology industry.  It is clear to me with over 10mm users worldwide that LinkedIn has crossed the proverbial chasm.  The company has clearly done a great job creating a strong revenue model around social networking and leveraging the technology industry to get started, but as I see more and more mainstream users join the service I wonder how big it can get and how it will play against the other players in the space.  LinkedIn has repeatedly stated that it believes people will have two profiles, one professional that is maintained on LinkedIn and one personal which is maintained on MySpace or Facebook.  I don't doubt that at this time, but I must admit that while Facebook has mostly been about friends and personal relationships, I have been surprised at the number of professional and business contacts wanting to add me as a friend on Facebook ever since it opened up its platform.   It will be interesting to see how these two services grow, how the boundary between friend and professional contact continues to blur for the professional, and whether Facebook makes a concerted effort to enter into LinkedIn's turf.  For example, why couldn't I maintain one profile on Facebook and only share the professional information with those in that network and the personal with those in another?  Expanding that thought, wouldn't it be great if there was a metaservice where you only maintained one user profile and you could check off which details were fed into which different social networks.  I would love to hear your thoughts on the subject.