The Electoral Map has a good rundown of the fastest-growing and fastest-shrinking congressional districts in the US. The upshot is that the Republicans are likely to make short-term gains after redistricting in 2012, thanks to new seats in red states like Texas, but the long-term picture may be different:
Democrats moving to states like Texas and Arizona might make those states more competitive and give [the Democratic Party] more seats at the state level.
Of note to Massachusetts is that none of the 25 "big shrinkage" districts are here, though most of our industrial-state rivals in the North have at least one district that's lost tens of thousands of people so far this decade. Illinois has five, and Michigan and Pennsylvania have four each.
Maybe we'll catch a break and not lose another seat in 2020?