If you create a post or moreso, a thread - you'll generally receive on the screen after you've hit send, a passage of text in black writing which I can't rightly remember what it says, but something along the lines of, "Thank you for creating this thread/post; ..." then there's some other words, that I can't remember - you'd think I would consider I'm on here so often.
But basically it usually has to be looked at by the moderator's default mechanism for any potentially 'dangerous words or connotations' so as it can be read and not offend anyone. Totally understandable on a site like this. If it's generally short and sweet and is all pretty cruisey, it'll go up pretty quickly.
If it's a long one (see pretty much nearly every post from me) then it can take longer to land on the site due to a bit more of a lengthy process for checking it through, etc.
With regard to if anyone has responded to your own post.
The same thing above still applies - so again, if someone replies, short and to the point, those posts can go up almost instantaneously (or within a minute or two). Longer ones, will take ... um, longer.
Hope that cleared up things a little better for you.
As it is the weekend though, I do get a strong feeling that things can take just a little longer than what they would during the week. Perhaps someone from B.B. can come and confirm that?