What's the best way to get started with OSGI? | What makes a module/service/bit of application functionality a particularly good candidate for an OSGi module? 


I'm interested in using [OSGi](http://en.wikipedia.org/wiki/OSGi) in my applications. We're a Java shop and we use Spring pretty extensively, so I'm leaning toward using [Spring Dynamic Modules for OSGi(tm) Service Platforms](http://www.springframework.org/osgi). I'm looking for a good way to incorporate a little bit of OSGi into an application as a trial. Has anyone here used this or a similar OSGi technology? Are there any pitfalls? 


@Nicolas - Thanks, I've seen that one. It's a good tutorial, but I'm looking more for ideas on how to do my first "real" OSGi bundle, as opposed to a Hello World example.


@david - Thanks for the link! Ideally, with a greenfield app, I'd design the whole thing to be dynamic. What I'm looking for right now, though, is to introduce it in a small piece of an existing application. Assuming I can pick any piece of the app, what are some factors to consider that would make that piece better or worse as an OSGi guinea pig?