One of the many articles on collaborative piano in the PPF is the excellent Don't Be Late! Rhythmic Visualization in the Collaborative Musical Ensemble by Scott Price of the University of South Carolina in the May 1999 issue. Here he looks at ways at energizing the rhythmic sense of an ensemble as a route toward solving the details of playing together.
A short quote from his article:
...one of the first things I have my students do is to put down their instruments and take their parts to an area where they have to rely on the visual score and aural visualization of the musical sound. They are forced to read the score and and know what sounds they desire before they touch their instruments. I often require that my students and their partners use nonsense syllables to vocalize their way through the rhythmic gestures of a section or the whole piece. By speaking the rhythm to each other, they are actively communicating the natural rhythm of the piece in a manner that is most natural to themselves.