I don't know if I read about this whilst sleepy, thus forgetting all about it in the morning, or if I somehow completely missed it during my scouring of gaming news back then, but it was confirmed last month that there would be no vehicles in Modern Warfare 2's multiplayer mode.
This makes me so damn happy, because now I can rest a lot easier knowing that Infinity Ward have a general idea of how to ensure this game is a sequel that's more of the same. I've even heard rumours that they've been getting in touch with the creators of Promod to ensure the mod scene have no issues coding on the sequel.
Here's the source: http://www.modernwarfare247.com/news/no-vehicles-in-multiplayer