Musk:

Tesla Motors was created to accelerate the advent of sustainable transport. If we clear a path to the creation of compelling electric vehicles, but then lay intellectual property landmines behind us to inhibit others, we are acting in a manner contrary to that goal. Tesla will not initiate patent lawsuits against anyone who, in good faith, wants to use our technology.

[...] Given that annual new vehicle production is approaching 100 million per year and the global fleet is approximately 2 billion cars, it is impossible for Tesla to build electric cars fast enough to address the carbon crisis.

I think I was saying something about Musk being a pretty cool guy. This is just further proof. I'm sure there are some strategic reasons for this move too, but I really believe that he's out to make the world a better place and this move will help. Anything to speed up the adoption of electric cars would be a win.

I agree with Dave Mark over at The Loop as well:

This is a pretty huge step. Some might see this as self-serving on Musk’s part, but I see this as altruistic, through and through.