Its obvious that Facebook clearly has a lock on college social networking and LinkedIn is quickly wrapping up the 28+ professional market but it's not entirely clear that its a generational gap. I'm inclined to think that, at some point, people just start getting more proactive and systematic about their career management and that's why they join LinkedIn.
Plus, Facebook hasn't quite mastered or had an interest in the idea of the professional profile. There's a section to fill out work information, but it's not exactly intuitive how you would show your drunken college pics to your friends, other people at your college, but not recruiters who may have went to your college. I think maybe they need a "Don't show to alumni" privacy feature, because many alumni recruit at their own schools. This is why, like danah, I don't believe in one network to rule them all. People are multifacted and they want to show different sides of themselves in different places. Facebook, as a community, may be best served just sticking to being a social service, even though I think that they could do a lot of good in helping young people reach out and help each other professionally.
Speaking of alumni, Facebook also hasn't been particularly aggressive in keeping alumni interested in the site. I've heard a lot of people say that they just don't use Facebook much after school, and maybe that's just natural. Plus, I'm not quite sure what alumni features would be. Perhaps they could enable people to publish alumni events and notices to everyone in the network via the newsfeed? Just an idea.
Keeping people interested in the site after graduation would be key to winning in the professional networking market, but I don't think that's where they want to go. They have setup work networks, but it seems like that's more about your friends from work than anything else. I fact, the other day, in trying to recruit for an entry level marking position, I tripped the spam alarm because I was sending a job post to a lot of young marketing majors. I was warned on the site, and when I contacted FB to tell them that I was a real person with a real job opening at a real company, and asked if that was spam, they very politely said it was and asked me not to use Facebook for recruiting. Recruiting and jobs seems to be a big business they're leaving on the table, and I'd be really surprised if they didn't make a move there. Prolific commenter Jeremy said that they should at least corner the internship market and I agree. They might just allow free internship postings and live off the ads around those pages. If they did that, I think they'd be well served to use Indeed to give themselves a huge head start in backfilling the database day one.
But, again, moving up the ladder to these types of professional tools doesn't seem to be on their roadmap.
On the other hand, LinkedIn trends older and hasn't made any headway at all into the college market. Career offices don't push its usage, and when you're just starting out and don't have much of network, the value of LinkedIn isn't immediately obvious. If I was LinkedIn, I would use the Facebook API to pull in your major, your school, your friends' names...not only to give younger members more value, but if nothing else than to signal the market that you never can start too early. I wonder if perhaps they really don't want the college crowd on LinkedIn, because their networks wouldn't add much and they'd likely take more than they would give.
So if I'm in college or just out, LinkedIn doesn't want me, because I'd be a mooch, and Facebook doesn't want to help get me a job, because that's not fun and social enough, so where does that leave me? Pretty underserved, I'd say. It's really amazing to me that one of the largest and most desperate group of job searchers, and the youngest and most technically savvy doesn't really have a place to go to start building professional networks.
I think there are two causes for this. First, there's a lot of self-fulfilling proficy going on with this age group. It is assumed, often in liberal arts schools, that career management is too early because they don't know what they want yet or they're still focusing on their education. So, what happens is that college seniors often find themselves illprepared to enter the workforce and they take the first decent job that comes their way.
Second, I wonder if today's MySpace Generation who grow up with recreational social networking has been trained to think of the internet as a place for friends and not really for careers.
Either way, I really think there's an opportunity for someone here.