LinkedIn, the networking site for professionals connect, has raised $12.8 million in venture funding.

The venture capitalists, Silicon Valley’s Bessemer Venture Partners and the European Founders Fund (EFF), an internet focused firm, placed a value of more than $250 million on the Palo Alto company, after the investment.

This catapults LinkedIn to the rarified group of networks that are actually worth something – though granted, this worth is still on paper – held on the books of venture capitalists, untested by the market.

The company raised the capital because it could do so on favorable terms (at higher values, a company gives away less of the company’s shares in exchange for an investment). Keith Rabois, the company’s VP for corporate and business development, said the cash will let LinkedIn experiment with various products, launching them and then killing them if they don’t work out. The company is already profitable.

The LinkedIn network currently has 9 million users. The company says the number is growing at 100,000 members a week, which suggests acceleration.