I've had a vibration on acceleration. Take a look at my thread from a few months ago. Flex disc was my main suspicion, but it turned out to be a bad half axle. This was diagnosed by the dealer. Completely took care of the issue.

A vacuum leak will give you a rough idle or vibration while stopped at a light for example, but it wouldn't be noticeable enough to shake the whole car while in the highway. That is more indicative of a drivetrain issue.