When you short a stock you are essentially creating a new shareholder. The person who held the shares in a margin account (the person from whom the broker borrowed the shares on the short seller's behalf) considers himself or herself a shareholder, quite justifiably. The person who bought the (lent) shares from the short seller also considers himself or herself a shareholder. Now what happens with the dividend and the vote? The company sure as heck isn't going to pay out dividends to all of these newly created shareholders, nor will it let them vote. It's actually fairly straightforward.
If and when dividends are paid, the short seller is responsible for paying those dividends to the fictitious person from whom the shares were borrowed. This is a cost of shorting. The short seller has to pay the dividend out of pocket. Of course the person who bought the shares might hold them in a margin account, so the shares might get lent out again, and so forth; but in the end, the last buyer in the chain of borrowing and shorting transactions is the one who will get the dividend from the company Tax-wise, a short seller's expense of paying a dividend to the lender is treated as a misc investment expense subject to the 2% of AGI floor. It does not affect basis (though I believe there is an exception that if a short position is open for 45 days or less, any dividends paid by the short seller are capitalized into basis instead of being treated as an investment expense -- check the latest IRS Pub 550).
Voting of shares is also affected by shorting. The old beneficial owner of a share (i.e., the person who lent it) and the new beneficial owner of the share both expect to cast the vote, but that's impossible--the company would get far more votes than shares. What I have heard is that in fact the lender loses his chance to vote the shares. The lender doesn't physically have the shares (he's not a shareholder of record) and the broker no longer physically has the shares, having lent them to the short seller (so the broker isn't a shareholder of record anymore, either). Only a shareholder-of-record can vote the shares, so that leaves the lender out. The buyer, however, does get to vote the shares. Implicit in this is that if you absolutely, positively want to guarantee your right to vote some shares, you need to ask your broker to journal them into the cash side of your account in time for the record date of the vote. If a beneficial owner whose broker lent out the shares accidentally receives the proxy materials (accidentally because the person is not entitled to them), the broker should have his computers set up to disallow that vote.