It occurs to me that not everyone may spend a lot of time visiting user forums and may not be clear about what a "Sticky" post is.
In forum software, the term "sticky" just means that the post will always remain at the top of the forum section that it is posted in. Its purpose is to allow the forum administrators to take certain posts and have them "stick" to the top of the list so that they will not move down as new posts are added. For example, this post and my "hello" post will remain at the top of the forum list until I remove them.
Generally, "stickys" are used for topics that the administrators think are important enough to have them remain plainly visible to the forum visitors. I'll shortly, for example, be adding a sticky post about using WorkingArtist with Windows Vista. We've received several questions about this, and a "sticky" post will make that information easily available to anyone who visits the forum, without having to search for it.