Linked In comes at this from the position of an online C.V./resume service that allows you to "connect" to people you've worked with. In theory it's a business version of Facebook, in practice it's actually a reputation service. I do not maintain highly active relationships with former colleagues and customers. We connect on Linked In because it allows us to keep in touch with little effort and verifies who we are, the roles we've held, and the work we've done.
Linked In have recently expanded their group functionality to create discussion forums so people can converse with "real" people. Sadly these groups are trending heavily towards spammy selling posts. There is no way to remove the noise from these groups and no obvious reward for high quality contributors.
The business model for Linked In seems to be selling premium access to user data for recruitment and sales professionals. In my opinion this is a short term model. They are really in direct competition with their customers. The recruitment industry exists because of a lack of quality information about potential employees and is ripe for disintermediation. They are also in competition with 'outside' sales professionals which represent a huge cost burden on B2B sales. The rewards for moving sales 'inside' are potentially huge.
Stack Overflow comes at reputation from the other side. They have created a high quality answer board for technical questions and with Stack Exchange have expanded the product into virtually any topic. Their key innovation is to reward high quality answers and to encourage quality contributors with incentives like badges and points.
Stack Overflow users generate a different form of reputation, they are verifying that they actually understand a specific subject. This is incredibly valuable because it verifies something that Linked In cannot: the ability to do something *again*. We've all worked with people who just scraped by, doing what they're told without necessarily understanding it. You can guarantee that those people could not generate a good reputation on Stack Overflow.
The business model for Stack Overflow seems to be around advertising and particularly job advertising via the Careers site. S.O. Careers allows users to create an online C.V./resume that is linked to their reputation. Sound familiar?
This is where they collide. Linked In has a lock on the verified C.V./resume side but the discussions functionality is poor. Stack Overflow has a lock on quality discussions and answer board functionality.
Building a reputation on Stack Overflow has some value but it's limited to that context. S.O. Careers may be relatively successful but it seems unlikely to eclipse Linked In in this respect, never mind the 800lb gorillas like Monster.
Likewise building a C.V. on Linked In has some value but participating in discussions is frustrating and has no clear payback. The depth of reputation is limited to fairly shallow "I'll scratch your back if you scratch mine" recommendations.
1. Stack Overflow adds social network functionality: seems unlikely to receive broad adoption for any number of reasons.
2. Linked In completely revamps their discussion functions to emulate S.O.: this would require their customers to recreate all of questions and answers that exist across all S.O. sites.
3. Integrate using APIs. Move Linked In groups/discussions to Stack Exchange and use Linked In profiles in place of re-creating a CV on Stack Overflow.
4. MERGE!!!! - I'm dead serious here. Merging these services would create a very strong network effect. It would be the natural home for professional questions and discussions and provide clear incentives for people to share their knowledge. The combination would pretty much own the professional reputation space. If this ever happens Monster are toast…
It's a new year, time for thinking big.