One of the XP values is Communication. There are many ways of communicating within the team, and with people outside the team. We generally prefer conversation for most purposes, but when it comes to trends, history, or sensitive subjects, a good approach can be what we in XP call a Big Visible Chart, or what Alistair Cockburn (Agile Software Development) calls an Information Radiator. A simple chart on the wall can bring important information to the attention of the team, the customer, and everyone else who passes through the area. The chart can provide important information, even politically sensitive information, without getting personalities involved or hurting feelings.
Read more: Big Visible Charts.