I made my three votes in the SO moderators election (or so I though) but I'm still being asked to vote. Have I missed something to post my vote, or does it just remain editable until the election is closed ? Its not clear.
If after your third vote you're told you have 0 votes left, then you're done and your votes are in. You can change your votes at any time.
Beware that clicking "2nd choice" next to a candidates name removes any prior "2nd choice". It doesn't intelligently bump your previous votes down to "3rd choice" and "no vote" or anything like that. But at any stage, the popup saying "X votes left" is the surest way to confirm that your votes are up.
The banner on top saying "Cast your final vote in the Stack Overflow 2011 community moderator election!" will remain there after you've voted. It's a general announcement banner that has no awareness of the votes you've casted. As Pekka puts it, it's "dumb".