The legendary glitching community behind pretty much every major glitch has confirmed that elevators do exist in the latest Call of Duty release, Modern Warfare 2.
Complete list of Call of Duty Modern Warfare 2 Glitches at this link:
Update 2: It is confirmed, new glitch found by us allowing players to turn themselves invincible. The glitch will not be released for the sake of maintaining the cheaters.
Update 3: New glitch on terminal to get HIGH above the map and FAR outside of it.