Interesting - I had been embarrased also about how my X-GF's daughter had acted in public. She had asked me if there was anything I could suggest to help her very active 5 year old daughter behave better. Besides suggesting a little more discipline with consequences, I got her a book from the library that had ideas parents could do to with children with hyperactivity problems.
One book I just picked up from the library for myself to read is called "How to talk so kids will listen & listen so kids will talk ". It sure cant hurt to find other ideas on how to better communicate with kids.