The Antares rocket, built and designed by Orbital Sciences, will have it's first test launch on April 17th, pending there are no check issues leading up to the date. It's being rolled out to the pad now in preparation for it's first flight. It will carry a mock capsule that simulates the mass of it's actual capsule to be carried in later flights this summer.
If this is successful, they will be the second company behind SpaceX to start launching their own capsule, and the second to fufill NASA contracts to deliver goods to the International Space Station.
The launch will be streamed on NASA TV Online.
Some more details about the platform: