jlcp ready for custom modules?

hi,

we are about to build a community software with some custom
functionality in addition to the more standard forum, user management,
buddy list and so on stuff.
the system should be based on j2ee and we would like to build on top of
some "standard" community platform. jlcp seems to fit nice.
my question that far is how well does jlcp support such a "custom
module" concept already?
more precise:
- is there a public (stable) api for such custom components?
- is there a public api to interact with jlcp provided services, e.g.
user management.
- is there something like extension point to add functionality or change
behavior for existing modules?

maybe not all of that is yet implemented, but maybe there are already
some design concepts, that we might help implement.

regards,
stefan