Without even mentioning that advertising frequently implies an "embelishment" of facts, one can assume that when Apple portraits someone who uses Motion (or FCP or DVD Studio Pro) they mean AMONG other things.... In the case you mention, it would be completely unthinkable for a specialized motion design studio like Mekanism not to use a combination of After Effects/Combustion and 3D applications... and Motion too.
Motion offers a revolutionary level of ease of use for complex tasks, but there is a lot of what AE does that it doesn't do at all.
While Mark is completely right (no 3D space in Motion), Motion 2 added a few tricks that make it a bit easier to fake perspective than it was before. The Basic 3D filter is one of those filters. At the same time, you have filters like Extrude which offers basic volume simulation, something AE doesn't do at all (if you leave the 3D Invigorator plug-in out of the equation). So each tool has its' strengths.
Adolfo Rozenfeld
Buenos Aires - Argentina
www.adolforozenfeld.com