London-based Playfish – which we speculated at one point was doing very well out of its social games on Facebook – has raised a whopping $17 million series B round led by Accel Partners and Index Ventures. This confirms the growing view that VCs will start to put more money into their strongest performing portfolio companies than into riskier early stage startups. Kevin Comolli, from Accel Partners and Ben Holmes from Index Ventures, will both join its board of directors. The company will now expand with four international offices and onto other platforms outside of Facebook. TechCrunch has more detail here.

Playfish now has over 10 million monthly active users on Facebook (around 1.5 million daily) and two billion monthly minutes of play time in under a year.

CEO Kristian Segerstrale is a big proponent of casual games and told me last month:

Social gaming is a very hyped area currently and there will be challenges ahead for sure, but I think the fundamentally new gaming behaviours we’re creating today will make a profound impact on the $50Bn games industry over time. And it’s that more than today’s numbers is what makes me excited about it all.