No undecided voter gives a **** about these polls. The only ones who do are partisans who decided long ago like us.
I'm not saying it will convince undecideds. But it's going to get a lot of positive coverage for Walker. "Walker way ahead! Walker on track for re-election!" etc. which may depress Dem turnout a bit/increase Rep turnout a bit. It's not going to be a huge difference of course, but in a race that will be decided by a knife's edge it could matter.
Definitely. That's why campaigns will occasionally leak internal polling that shows them in a dead heat or up by 1 when public polling is showing them falling behind: the supporters on the ground demand a reason to believe they have a chance in order to keep them willing to go out and volunteer and vote.