IE will transfer or duplicate a bottom margin from a static element to below a float. Each example has a clearing div of height:10x.
The above two examples show the same as standard complaint browsers, but in the next example, because the float is of greater height than the margin-top of the element above, IE now decides to transfer/duplicate the margin. This does not happen in standard compliant browsers.
In the next four examples, the wrapper with the grid background will extend down by 100px. This does not happen in standard compliant browsers. The grid background is also not stable (try moving a window over).
In the next example, the wrapper with the grid background has a top and bottom padding of 25px. Now IE renders the same as standard compliant browsers.