I have started to contribute a set of interfaces that describe runtime metadata exposed by a portlet.
The word portlet here is to take with care as it can be a portlet container or an instance that points to a portlet container and is exposed. In particular an instance would return the same data as the portlet container it points to would but with a specialization (preferences).
The package is org/jboss/portal/portlet/info/*
Then later this information will be exposed by the portlet invocation bus.
A quick check of the interfaces didn't reveal glaring issues. I suggest starting with that and see how it goes. We'll grow things from there.