The good economic numbers made the whole immigration thing, but a small blip on the radar screen this particular election cycle. At this point, a hardline on immigration is a net loser. That very well could change depending on what happens with the economy, but right now, it's not a winning issue for the GOP.
It sure as hell isn't a winning issue if 12 million illegals become citizens and have the right to vote.
Immigration should have been played as a security issue, which it is. Forget the economics of it, it's a matter of controlling your borders post-9/11. The Dems were all about shovelling money at "homeland security" because the make-work/public-employee union aspects of it were something they instinctively understood. If GWB had listened to Tancredo, et. al. the Dems would have been in a real political bind on the border.