I'd say it is a very good idea, like clicking on the banner to go "home" it brings some of the site's look and feel into stanard without changing the charachter of the site.
Have a "Cast your vote" with no visible data, but with a "See current vote tally" option that allows a later "after seeing it" vote.
Then if someone choses first to "See current vote tally," - do allow them TO vote after seeing it; if they're surprised or outraged or agree with it, then STILL let them vote if they hadn't. It's not a "contaminated' vote because it is still a valid opinion, plus a vote that evokes a viscreal disagreement must be counted.
But show us the "Blind/naive vote tally" along with a "Full vote tally" and a "dirty vote tally."
Would be interesting...
Interesting idea. If the purpose is to collect votes which are not contaminated by the way previous voters have voted, then having a "Show Results" button would open a loophole, and most attempts to close that loophole would open other loopholes. It seems the only way to close all possible loopholes would be to not have a "Show Results" button, and to only show the poll's results to logged-in members after they have voted.
As others have suggested, clicking the "show results" could nullify your ability to vote. That would be my preference. This would also require hiding the results from anyone who isn't logged in.
Now a really determined user could use a sockpuppet account to get around that, but I mean it's not like we're voting for president here :). Also one could currently use that approach to skew poll results currently anyway.