I just made a 'map' bbcode and put your code, unchanged, in the replacement text area. I had to click the "No" for "Remove if Empty", but other than that i used the default settings. Then in my post I put [map][/map].
But I also went back and tried the style thing, and that also worked - so you *can* have a style in an iframe tag, and setting the min-height seems to work. So to answer your previous question, it would go something like this:
Code:
<iframe style="min-height:480px;" width="640" height="480" ....etc.
Edit: Unfortunately, I see that it didn't work...maybe try taking it out of the CODE tag?