GenkiGenga Thanks for the .capx but that has the same problem as Asmodean's - The player hovers for an undetermined or fixed amount of time instead of for the remainder of the jump.
Also worth noting that if the player is jumping while moving, hits a ceiling, and then moves past the ceiling, the jump will continue upwards (provided he's not at the falling end of the complete jump arc).
I think the only way to properly do this is to modify the platform behavior or make a whole new jump mechanic with events :T hmm..