I say Q2, mostly because the Census Bureau will add 1 Mio. workers to the rolls in Q2 2010 to conduct the 2010 Census.
Unemployment is likely to drop by 0.5% during this quarter. Itīs likely that the rate will increase again somewhat in Q3, but many employers might start hiring again during these quarters, so it could even stay at about 9-9.5%. The Census hiring effort might actually benefit the job market somewhat, because many employers might think: Well, he/she worked for the Census Bureau and is a motivated worker, instead of being a lazy unemployed bum and sitting at home. Therefore some employers could be more likely to hire these people once they are finished with the Census.
http://www.nytimes.com/2009/12/19/us/19census.html