Agile and Scrum project teams can adopt many different structures. In her blog post, Elizabeth Harrin gives a good summary of five structures that could be used by Agile teams based on a presentation made by Catherine Powell at the Oredev conference.
The five Agile team structures presented are:
1. Team generalist: members can perform any task at any time. Might be difficult to scale.
2. Team specialist: members perform only specific activities. Difficult to manage successfully.
3. Team relay: when transitioning to Agile, sprints are broken down by discipline
4. Team biathlon: everyone changes jobs per sprint.
5. Team handoff: the work is handed off between teams over time. One team do the design and another the implementation.
Read the complete blog post on http://www.pm4girls.elizabeth-harrin.com/2013/02/5-team-structures-for-agile-teams/