The Republicans just got the candidate they wanted to run for Senator in Montana in 2012 -- Congressman Denny Rehberg. Montana has only one House seat, so Rehberg has run and won statewide 6 times.
Montana Senator Jon Tester, whose term is up in 2012, won very narrowly in his only statewide run in 2006 over Conrad Burns. Rehberg has run ahead of Tester in early polls. This is now a seat where the GOP's chances are even or better.
Throw in North Dakota, where Democrat Senator Kent Conrad is retiring. and the GOP has two excellent pickup opportunities early in the campaign season.