No, in fact I'm not sure that the "Rhino for Windows Category" topic is anything more than a test of putting a conversation in a category.
Topics in Discourse are like threads on the newsgroup - feel free to start a new one with any topic you want to discuss.
Discourse lets you optionally assign a category to a discussion. This should let people decide to pay attention to, or ignore, different areas of discussion.
We're just learning the ropes here, too - keep the questions coming!