A stealth-mode San Francisco outfit called RPX, which calls itself a “patent acquisition services company”, has taken an undisclosed funding from top firms Kleiner Perkins Caufield & Byers and Charles River Ventures.

Details look thin on exactly what RPX does, but the general outline seems to be a risk mitigation consultancy that can help companies protect their patents for less money. Patent litigation (often brought by unsavory characters known as patent trolls) often costs big companies millions a year, or more. [Update: RPX contacted us to say its services aren’t about protecting companies’ patents, but rather reducing the impact of non-practicing entities, i.e. patent owners who don’t manufacture or use their inventions.]

The company says that it plans to launch its service in October.