LinkedIn gets more funding, why?

LinkedIn … now here is a company, that came to the social networking trend early, stayed focused on the business market, and now is well on its way to clock $100 million in revenues. It has just crossed the profitability threshold and is making money pretty much every which way it can.
A valuation of $250 million is being put on the company … and yet it goes ahead and raises almost $13 million in fresh venture funding, and no one asks the question: why? Why does it need fresh capital from Bessemer Ventures and European Founders Fund?
Somehow I don’t buy the “new product experiment” argument made by Keith Rabois, LinkedIn’s VP for corporate and business development. Time to give Reid Hoffman a call, and ask for myself.
Update: Reid Hoffman has left a long response to what LinkedIn is going to do with the money in the comments. Here is a quick link, if you want to understand where LI is going.