When someone jumps up into a vehicle and takes control of one of the weapons do they incur the -20 penalty to shoot if they don't have Heavy Weapon Training?

Yes they do. Has vehicle listed in the book for that talent. Answered my own question.

nethru said:

I believe it also mentions somewhere that the pilot of a vehicle is assumed to be able to fire any pilot operated weaponry without penalty, it's just gunners or vehicle weapons on vehicles you aren't trained in, that will give penalty.