Here are Polidata's estimates of which states will gain and lose House seats and electoral votes based on extrapolations from the 2007 Census Bureau population estimates. Here's a list of which states are projected to gain or lose seats, for Bush 2004 and Kerry 2004 states.
Bush 2004 statesKerry 2004 statesArizona +2California -1Florida +2Illinois -1Georgia +1Massachusetts -1Iowa -1Michigan -1Louisiana -1Minnesota -1Missouri -1New Jersey -1Nevada +1New York -2North Carolina +1Oregon +1Ohio -2Pennsylvania -1South Carolina +1 Texas +4 Utah +1 TOTAL +8TOTAL -8Which is to say that, under the new electoral vote distribution, Bush's 286-to-252 electoral vote margin in 2004 becomes 294-to-244. Bush would have lost in 2004 if Ohio had not gone his way; under the projected post-2010 apportionment, Bush would have won 276-to-262 if Ohio had not gone his way. The demographic trends reflected in these projections would not prevent Barack Obama from being elected this year and re-elected in 2012, but they would make it marginally more difficult. Demography, modestly, favors the Republicans, and more than modestly over the long haul; see my May 2007 article in the Wall Street Journal.
Note: Polidata projects California to lose one congressional seat. This may or may not happen. But if it does, or if California just stays even, this will represent a stark reversal of a very long trend: California has gained House seats in every Census-dictated reapportionment since it was admitted to the Union in 1850. Immigrants are still streaming into California, but the domestic outflow is balancing that off.