"Our next big update is our SDK, which will open development capabilities to experienced 3rd parties, freeware creators and anyone who wants to try their hand at bringing the experiences they crave to Flight Sim World. It’s an exciting prospect and one we couldn’t have achieved without the feedback of the 3rd party developers who’ve brought their content into FSW. Releasing the SDK will be one of the milestones for the continued development of Flight Sim World."

And here's the link.