It would be so cool to have a sexp that would switch player control to another ship.
and also a way to let the mission designer have complete control over some of the ai ships. (good for cutscenes)
You can already mimic that with change-shiptype (or whatever it's called)...
I'm not sure if I released it yet, but in the last version of my capship control-test, the ability to switch to a fighter is certainly included (check the version at freespacemods.net, it might have this already) - a new ship is then created to take over the capship you just "left"... don't know if I already implemented landing, though.