BLS Job numbers always produce headlines and market impact when they come out while later revisions to the figures slip out later. During normal economic times these revisions are fairly minor. However, the fact that these figures are based upon historic trend estimates of economic activity creates very innaccurate figures during serious recessions.
This is very true now.
August 2008: Initially 84,000, revised to 175,000
September 2008: Initially 159,000, revised to 321,000
October 2008: Initially 240,000, revised to 380,000
November 2008: Initially 533,000, revised to 597,000
December 2008: Initially 524,000, revised to 681,000
January 2009: Initially 598,000, revised to 655,000
February 2009: Initially 651,000, as released today.
The biggest single distortion comes from the BLS's guestimate of the number of firms created and going out of business in a given period.