Just in time for last week launch of the DirectTV-11 satellite, MajorTom and his team have released their first version of a long overdue Sea Launch addon for Orbiter. I have been playing a bit with it and enjoying it. The launch platform could use more detailing (it's planned for next release), but the automatic guidance works well in both delivering the payload to a parking orbit then boosting it (thanks to its 3rd stage Block DM-SL) into a Geosynchronous orbit. Haven't been follow much before the Zenit-3SL launches, I had in mind that the 3rd stage was used to insert the payload into its definitive orbit, but in fact it is not the case since the payload is inserted into a elliptical orbit with an apogee at Geosynchronous altitude and a low perigee (<200km) . It is then up to the satellite to raise its perigee over the course of several burns.