UPDATE:

The last transaction on 7th was at 22:50:53, so their window should be at least an hour longer.

Seems that about 3 BTC went to the Good Samaritan, who then returned it to blockchain.info: https://bitcointalk.org/index.php?topic=581411

Anyone who deposited after 7th got their deposits stolen immediately.

All this time blockchain.info showed me completely different view of things and a valid balance, so I was unaware that somebody was stealing all new deposits.

Users #96, #387, #500, #1176 had their deposits stolen for the total amount of 4.72614335 BTC.