It doesn't mean anything for '06 if the dems win both. They were both democrat positions, so they gain nothing by keeping them. Status quo. If the Republicans win either, its' a gain. Plus the fact it's an off year election with low turn out. If one or both were Republican positions, and the democrats took one or both, THAT would be important for '06. But since they're both democrat positions already, if they stay democrat, all that means is they managed to finally stop the bleeding in a couple of instances in an off year election.
It depends on the margin. If Kaine embarrasses Kilgore with an eight- or ten-point win, it could portend deep voter dissatisfaction with the GOP.