In a changing market, Can you tell your clients
whether it is a buyers market or a sellers market or does this violate any code of ethics rules?Thanks

I can't see how it would. You must inform your clients of how things are working. We are in a buyers market here, but you could argue that it's a sellers market since owners of homes have experienced more appreciation in the last 3 years than ever in the last 10 years.
I tell people that buyers are able to be choosy today. That helps sellers make sure all objections are removed from their home. You don't necessarily want to phrase it the same way to a buyer, though; or they will sit on their hands until after Christmas.
--A

I don't see how it can violate the code of ethics. Maybe you can read it to understand what it contains. http://www.realtor.org/mempolweb.nsf/pages/Code?OpenDocument