Dave Warnock replies to my post on little apps:

Absolutely little apps. But why do I need to run them all myself. There are plenty of options coming such as SXIP that will allow me to use someone elses application (running elsewhere) for login.

One of the good things about building your site(s) as a community of applications instead of a community of components in a framework, is that you've created a decoupled system where migration to and from these external services is not a painful or architecture-changing process.