It might make sense for the few companies to stir up some community. Promote D to students and get job candidates in return. Build a website mostly consisting of a job board and events calendar. Integrate Twitter, mailing list, etc to keep low-traffic connections to people.
Wouldn't use it. If you have a question, you'll get more people reading and answering it here. If you want to participate in language discussion or development you'll have to do it here either. Only useful topic in a german subforum would be events in german speaking countries. Just mark them with [German] in the topic and post them here. If it starts to annoy people, we're big enough to justify a german forum.