I thought it did, based on the evidence here. Now Matthew Shapiro and Joel Slemrod have a new paper that says it didn't. From the NBER digest abstract:

[...]Only one-fifth of the survey respondents said that the 2008 tax rebates would lead them to mostly increase spending. Most respondents said they would either mostly save the rebate or mostly use it to pay off debt. The most common plan for the rebate was debt repayment.

[...]Because of the low spending propensity, the rebates in 2008 provided low "bang for the buck" as economic stimulus, Shapiro and Slemrod conclude. Low- income individuals were particularly likely to use the rebate to pay off debt. Shapiro and Slemrod speculate that adverse shocks to housing and other wealth may have focused consumers on rebuilding their balance sheets. The authors note that, given the further decline of wealth since the 2008 rebates were implemented, the impetus to save a windfall might have become even stronger since their survey was conducted.