Does this picture remind you of your last project?  This is one of my favorite comic strips about project management communication, or miscommunication.  I first came across this comic strip about 6 years ago, it was posted outside of a cubical at a new client site.  I thought it poignantly demonstrated how easily miscommunication can occur in a project.

Whenever you have a team of people working together for a common cause, it becomes imperative that the right hand knows what the left hand is doing so that there is no miscommunication.  Certainly there will be times that it happens, but those times need to be minimal.