Real gross domestic product – the output of goods and services produced by labor and property located in the U.S. – decreased at an annual rate of 6.2 percent in the fourth quarter of 2008, (from the third quarter to the fourth quarter), according to preliminary estimates released by the Bureau of Economic Analysis. 
 
These GDP estimates are based on more complete source data than were available for the advance estimates issued last month. In the advance estimates, the decrease in real GDP was 3.8 percent.
 
The decrease in real GDP in the fourth quarter primarily reflected negative contributions from exports, personal consumption expenditures, equipment and software, and residential fixed investment that were partly offset by a positive contribution from federal government spending. Imports, which are a subtraction in the calculation of GDP, decreased.
 
Most of the major components contributed to the much larger decrease in real GDP in the fourth quarter than in the third. The largest contributors were a downturn in exports and a much larger decrease in equipment and software. The most notable offset was a much larger decrease in imports.
 
Final sales of computers subtracted 0.01 percentage point from the fourth-quarter change in real GDP, the same contribution as in the third quarter. Motor vehicle output subtracted 2.04 percentage points from the fourth-quarter change in real GDP after adding 0.16 percentage point to the third-quarter change.

More details here.