rtcvb32: I read a wiki for Pioneer saying it was still in development and had few missions available, so this isn't really a big surprise... I just hope their efforts get combined and one team doesn't do their own thing leaving the other to update to try and keep up...
From what I gathered in the SpaceSimCentral forums Scout Plus is updated regularly from the code base of Pioneer. The wonders of Git branching ;-). Scout+ is lagging a little behind (seen on the interface which is an older version of Pioneer, but the next version is already announced.
There's also another version called Genesia. In this case, Genesia is actually the original, and Pioneer has been a branch of it. I think Genesia had been abandoned for a while so Pioneer took over as the main branch. It seems it's now alive again, also on SSC.