“OKCoin is currently suffering from malicious cyber attacks and as a result, some services may be suspended, Sorry for the inconvenience.”
Note that the problems conveniently started as the price started to go down. That's deeply suspicious. Many Bitcoin exchanges have gone under because they speculated with customer funds and guessed wrong. When that happened, suddenly delays started to appear. Remember Mt. Gox.
Worse, OKCoin offers "leverage" and derivatives. If they mismanaged their counterparty risk, OKCoin could lose big.
If you have any assets in OKCoin, get them out now.
Has OKcoin said it will compensate people who were margin called because they couldn't access their accounts to close positions? I'd hate to watch all my money going up in smoke because an exchange was down. I lost some money in that situation once, but not everything.