Looking at the useful lists compiled by Dan Filler, one can see that in each of 2007, 2008, and 2009, there were around 125-130 lateral moves (give or take) each of those years. 2009 was still comparable to earlier years, no doubt because these kinds of hires, especially those with tenure, are often 1-2 years in the making. The initial effects of the economic collapse will be felt, I imagine, in hiring decisions made this year and next. Already there are reports of some major law schools that made few or no lateral offers to visitors due to budgetary concerns. (Yale, interestingly, increased its 1L class this year by more than 10% to offset lost endowment revenue.) My guess is the Filler list for 2010 will be noticeably thinner than prior years, but we'll see.