I’m faced with a challenge of leading two (currently) separate .NET development groups with different development strategies. One group is developing on the .NET Framework 2.0 (with maybe a few applications on 3.5). The other group immediately adopts any new framework that comes out, and begins coding any new applications with it (they are running 2.0-4.0 applications). For this last group, applications written in an earlier version than the latest framework do not get upgraded.

What is the current school of thought when it comes to a company developing web applications on when to adopt a new framework, and whether to migrate applications built on previous versions to the latest framework or not? Years ago the thought was to wait until the technology became mainstream - but that doesn't seem to apply much now with .NET.