Hi Peter,
Yeah - the intention is that all the conversations (except private messages and "closed" groups) are public, but to post, you need to be a member. The idea being that - as we support each other in the forums - as many people can benefit from the discussions as possible, incl. Google users finding relevant posts. Plus, if everything was private, people would have no way of knowing if the community was any good without joining first. If you're worried about personal privacy, it's possible to change your username to something more obscure (e.g. not your name)... Let me know...
Cheers,
Niki