QUOTE (WearzManySkins @ Jun 7 2008, 06:06 PM)

Rigger Black Book page 95
Pure Vector-thrust or combination vector/ground effect drive
So that leaves the Devs some wiggle room as for what one is.
I don't see the confusion. Any vector thrust vehicle can operate in ground effect, assuming it has sufficient response time to avoid turning into a giant Lawn Jart. Heck, every airplane goes through a "ground effect" phase during take off and landings, it is apparently one of the hardest things to learn how to deal with as a pilot.
Let's take a hypothetical Banshee and say that in pure vectored thrust mode (i.e. at altitudes of more than a hundred meters) it devotes ~80% of power to lift and only 20% to thrust. Now it descends to ground effect elevations where its "lift" is maybe twice as efficient, meaning it can devote a mere 40% to lift and 60% to thrust. Barring differences in air density, in ground-effect mode the Banshee would be 3x faster. It also, of course, has to dodge trees, buildings, hills, and would give a much more roller coaster like ride.
IANA aerodynamic engineer so I don't know what the actual boost in "effective lift" ground effect gives, especially when you're discussing a vehicle that is relying on jet exhaust rather than wing-based lift, but regardless, the general logic will hold.