I wonder if it might be a useful architectural change to implement a dialplan plugin infrastructure. This would also make it easier for other developers (like me) to add dialplan functionality without needing to get in the guts of the main project.
It would also mean that modules with other license models (proprietry, or GPL) could be developed and distributed independantly of the main project.
I already have some changes in progress that I will submit as a patch shortly. If anyone has any input / ideas then I would be happy to incorporate.
I am implementing the infrastructure using MEF (http://mef.codeplex.com) and it will basically allow the user to drop a dll into the plugins directory and the methods will be avaialable in the dialplan.