Actually, Rasmussen will be polling some key states/races weekly before the election. I presume Allen/Webb will be one of them.
I am tempted to agree that VA Senate will be a key race over the next month or so, as I have a feeling this Allen/Webb race is much closer than it was in mid-July... but somehow I think VA will begin to become less competitive as time goes on and I see races like TN becoming more competitive in the fall.