Ukraine's Supreme Court has declared the elections fraudulent and nullified the result. A new (and hopefully clean) runoff election is expected to be held on December 26th. It's a victory for democracy, and for all the thousands of people who turned out in Ukraine to demand and defend it.
Now the task is to ensure that the Ukranian government doesn't get to fix the election a second time. But they'll be under intense international scrutiny, which should help keep abuses in check.