It's just a discussion. They monitor it all like any part of the forum, and may or may not choose to take your idea, if it works with what they have in mind. They won't respond categorically, and they don't just say "yes, yes, no, yes, no, no" etc.
Think of it as an open forum (no pun intended) for bouncing wishlist ideas off of other community members, with HTC listening.
They HAVE pulled a number of good ideas from the wishlist forum, FYI.