No such report?

Republicans in Congress have been citing a Congressional Budget Office report stating that most of the money in the proposed economic stimulus package wouldn't be spent before 2011.

There's no such report. There are some unpublished figures that the CBO gave to some members of Congress, but they don't prove that. They apply only to the portion that the Appropriations Committee deals with (not with the Ways and Means and Energy and Commerce portions), they're based on a previous version of the bill, and the CBO is recalculating them.

Ryan Grim explains it here.

Common sense should tell anyone that investment in infrastructure will take some time to gear up. You don't just run down to Walmart and buy a bridge, a highway, or a national fiberoptic network. Even repairing what we've got isn't instantaneous.

But that's a good thing. Including big infrastructure investments in the plan ensures that we won't waste all the money on crap from China.