I'd like to read about these, particularly about how they could be Constitutional, but I can't seem to find the correct words for a Google search. Would you post a link, or possibly a set of words to search for?
http://www.rcfp.org/ogg/index.php provides an outline of open meeting laws by state.
Actually, many states have open meeting laws where, if it becomes clear that politicians met and discussed certain topics, it is a crime, and it's punishable.
They don't often get used, but I think that the threat does alter behavior at least a bit.