Here's an excellent brief article on 15 characteristics that help make for success. Naturally, one is on communication which I quote:
Whether you call it communication, teamwork, or interpersonal skills, this trait is often an essential component in what separates those who are successful from those who are less so. To get what you want, you need to be able to communicate your goals and ideas to others. Good communication skills will make you better able to negotiate, sell your best attributes, and form lasting relationships that can help you build a better career. Of course, communication isn't just about talking. It's also about listening and keeping your ears open to new ideas and potential problems.
This site also has some interesting links relevant to communication effectiveness, quotations about communication, the art of conversation, and more.