Will you guys be converting the two JavaScript libraries to TypeScript?

Yes, it's on the horizon to do.

Is there a target release date for the TypeScript definitions?

I've started working on my own, but it would be great to have an official release.

We don't have an official release date. We still have to define our plans for the next release/improvements of the libraries. Now we are focused on fixing some issues with the code we just released, improve the directory structure and make sure all libraries can be easily built.

We will post an update as soon as we have a concrete plan for features such as TypeScript support.

Can't you release a rx.d.ts now and an rx.ts when TypeScript 1.0 is released? It would really help the community.