I had a thought that maybe it would be possible to show this by informing you of the state in a text box when you hover the mouse cursor over a wire - In a similar to the texts that you get when hovering over a component. For multibit wires you could have a list of the state of each bit e.g: B0 = 1, B1 = 1 etc.
Just a thought, but it would be rather useful for finding bugs.
![Smile :)](./images/smilies/icon_e_smile.gif)
Tom.