This can be a cautionary tale or one of hope, depending on perspective.
Yesterday, I ran this poll, brimming with confidence:
Rasmussen. 9/5. Likely voters. MoE 4.5% (No trend lines)
Gilmore (R) 34
Warner (D) 54
Davis (R) 30
Warner (D) 57
An old friend reminded me of this poll:
Rasmussen. 12/7/05. Likely voters. MoE 4.5% (no trend lines)
Allen had a 31-point lead less than a year before the 2006 elections. So we can never get too comfy if we're way ahead, and we shouldn't always despair if we're far behind.
In politics, things can change overnight.
Update: Obviously the dynamics of a Mark Warner matchup are different than those of the Webb/Allen race. The point wasn't that they're the same. The point was that in politics, things change and that while we can celebrate the good polls, those polls aren't everything. Campaigns still need to be run.
If the Draft Webb movement had taken this Rasmussen poll as gospel, we would've given up on Webb and ceded the race to Allen. We didn't. If the Allen people hadn't gotten cocky and overconfident after polls like this one, they wouldn't have been working on their presidential effort, telling people in Iowa that he wished he'd been born there and that he was running for president because he was bored of the Senate.