It will be up to each team to decide on the particular team organization that will be used. There will be no requirements for the team to use a particular set of roles. The following is a set of tasks that each team will need to cover. Past experience with senior project teams has shown that the team needs to explicitly assign responsibility for these tasks to a team member. If that is not done, then the task is not completed consistently. If noone feels responsible for a task, noone will do it.
Team Coodinator/Leader - whether you want to call this person the team leader or not will depend on the team. A fully democratic team often lets things fall through cracks because no one feels the responsibility for keeping track of what the team needs to do and making sure that one or more team members are responsible for completing it.
Sponsor Communicator - it works better if there is one person who primarily handles communication with the sponsor. Some sponsors may say that anyone on the team can contact him or her. Even if the sponsor says that, the team can still use a single point of contact with the sponsor. If the sponsor has a question, he or she may not know the correct team member to contact. If all questions go to one person, it is known that that team member has responsibility for making sure that an answer gets back to the sponsor in a timely fashion.
Website Coordinator - it really works best if one person is responsible for updates to the project website on the department server. Sponsors will often want to use this as the mechanism for receiving project updates, weekly reports, and artifacts. Someone needs to have responsibility for getting the latest material from all the team members and doing updates on a regular basis. Some of this can be automated by detecting updates to a website module in the project's CVS or SVN repository.
Meeting Scribe - some development methodologies may emphasize short meetings where full meeting minutes may not make as much sense. From almost every meeting, no matter what the development methodology, assignments of tasks to team members, with expectations on the completion time frame, will be made. It is important that these assignments and completion commitments be captured from every meeting and posted for the entire team to see. If that is not done, it is very easy for a team member to not complete a task claiming "I did not know I had to do that." To maintain a consistent style in reporting assignments, selecting one person to be responsibile for capturing team assignments works best.
Other task roles will be described as they are identified.