The rate announcement is not the surprise: virtually nobody expected a cut which would have taken the deposit facility to a negative rate and the monetary Twilight Zone. Where the surprise will come is what Draghi announces at the press conference in 45 minutes time which we will livestream when it starts.
From the ECB [3]:
2 August 2012 - Monetary policy decisions
At today’s meeting the Governing Council of the ECB decided that the interest rate on the main refinancing operations and the interest rates on the marginal lending facility and the deposit facility will remain unchanged at 0.75%, 1.50% and 0.00% respectively.
The President of the ECB will comment on the considerations underlying these decisions at a press conference starting at 2.30 p.m. CET today.