There have been a few issues with BitMarket account details being stolen (along with the bitcoins in those accounts) and yet other accounts being mysteriously frozen without explanation or response from support.
It now appears that those concerns were justified, in a thread on BitcoinTalk the user M4v3R who is the Owner/Operator of BitMarket made a post announcing "Right now there are 1786 BTC pending withdrawal, which I can't honor..."
M4v3R goes on to explain that he considers the problem with the 1786 BTC pending withdrawal (approximately $24,111 USD at today's rates) is his own fault and explains that the difficulties began when he decided to provide a hedge fund service using his previous trading experience and yet another bitcoin service, Bitcoinica.
When Bitcoinia went offline and subsequently into liquidation on August 1st, 2012 19,980 of BitMarket's clients bitcoins went with it. BitMarket did not decide to inform its users it seems.
M4v3R is asking for donations to be sent to 1Km5GFMat1DXcbvMTeH9ZvLGKvFCLBA9dM and is now looking for investors to bail BitMarket out."