In the current version (Q3 2011), when the user enters a value below the specified 'Minimum', the bound property is updated to this value.
In Q2, the source was also updated first to the wrong value, but afterwards a second update occurred using the specified minimum value.
The current behavior is just completely wrong, while the behavior in Q2 is also not really expected as I would expect of the control not to update the source to a value below the minimum in the first place, but directly to the minimum value.