I had an interesting occurrence happen in the Forums a couple days ago. I had a reasonable reply post appear from a newbie, which I approved for posting. His next 10 posts were totally spam. Fortunately, I had not yet removed him from the "Newly Registered" group, so none of those posts came through to the board. But, this means I will not be approving newly registered users immediately for posting without moderation. It'll take more than one post, and I'll be evaluating them for both content and interactivity.
Second, there appears to be a bug in the post counting routine in that it only seems to count posts made by fully registered users, not those approved in the Newly Registered group. I use the post count along with the date registered to control which accounts get pruned from time to time (registered after a certain date and post count equals zero.) This means that some Newly Registered users with approved posted comments may accidentally be pruned (deleted) if I don't catch their name in the prune list. I try to check it thoroughly to prevent that, but I can miss things. My apologies if that happens to you. Please remember that it's not intentional in any way
So for you newly registered users, don't be afraid to post and interact with the other forumites (ooh, sounds like an alien race in a sci-fi movie!) We don't bite, I promise. And I have my spritzer bottle if the barking gets too loud.