PAC (Presentation-Abstraction-Control) is a kind of MVC pattern.

Compare to MVC, the control/model/view is even more separated. Two examples of PAC are available on the subversion repository, one is in C# (demopac/logger) the other one is in C++ (demopac/counter).

The PAC model is used in WengoPhoneCSharp? and WengoPhoneNG?

PAC permits to thread model and presentation components separately thus allows to show the presentation component before the model has been fully initialized. WengoPhoneNG for instance seems to start instantaneously.