<p>I would really like to use SpringSource dm Server, but our customer requires us to run our apps on their application server (Websphere). Is there a way to integrate SpringSource dm Server with other application servers? At least dm Server is build on OSGi, and many other application servers (including Websphere) are based on OSGi as well. Is it possible to run a SpringSource dm Server as a websphere component?</p>

Spring DM is deployed on a Knoplerfish OSGi implementation.
Websphere is deployed on an Equinox OSGi implmentation.
So the question becomes - are the two interchangeable? They both support R4, so I would say, yes, they are.
The next question would be to check dependencies, particularly with respect to things like HttpServices.
I would say this would be ok, but I think the final proof would be try deploying it. Easiest would be to drop the bundles into a Websphere deployment. You'll need your bundles and whatever spring bundles you're using.