VG247 got word
from Infinity Ward's Rob Bowling that initially, Call of Duty: Modern Warfare 2
did have co-op gameplay for the story mode. Unfortunately, they found it to break the cinematic experience that they've been known for so they ditched it and put it in it's own separate gameplay mode.
Spec Ops will let you play with another in some co-op specific missions in the game though. The feature was born out of the dispatched co-op gameplay mode for the story and I hear it's a lot of fun. I can't wait to check it out.