While i have read the thread on replacing the architecture of Sitefinity with MVC, that is not my suggestion. Instead of outright replacing asp.net forms with MVC I would love to be able to use razor view syntax when rendering content widgets on the front end. Razor syntax has proven to be much more friendly for rendering frontend content and produces much cleaner html.
Here is an example of razor views being integrated in to SharePoint which is also based on asp.net forms.
Since Sitefinity 4.2 is already .net 4.0 this should be a much more straight forward implementation.
Razor has already been used to build a templating engine outside of MVC which is available on codeplex.