Organizing your IT Department by creating subteams is one of the best way to promote leadership and delegate some of your admin roles to the sub team leader. However, one has to plan the proper setup/teaming for these can cause conflict and miscommunication. There are several ways to approach such, depending on how it fits your organization.
This means teaming up your department members by the platform they know best. ASP guys can team up, Java/Open Source team and Flash team for example. There is a potential loophole in this kind of setup since some platform can do the same things like the other platform. So competition between who will do what may result to conflict and different teams may develop a version of the same application in different platform just to prove whose better thereby waisting time and resources.
Team of Analysts, Team of Project Managers, developers, testers and documentation specialists. If you want to set it up this way there is a possibility of a tier-2 subteams for specific projects involving many roles thus creating another layer and you managing more teams.
This is setting up your development team by way of your company’s major business processes. Accounting, Sales, HR etc. This is by far a better approach since development teams can just focus on the process they are assigned to and build projects on it.
A combination of Process Specialization and Project Role is personally the best approach. You can setup your team by major business processes and assign roles to each team members based on what he/she do best. Accounting team can have a Project Manager, Analyst, Developers, Testers and Documentation Specialists. Sales and HR team can also have the same setup. For cross-functional projects (projects that involves several business processes), one has to evaluate how major the roles are for each team and team leaders of those who has minor roles can just assign a point/contact person for his/her team as a resource to that project.
You can always find a better approach in organizing your IT Department, what matters is that it fits and adds value to your organization.