It's great when people announce they're leaving. Better still, they'll create threads to announce they're leaving.
It's like, if you leave, at least have the good sense not embarrass yourself by announcing it.
You may think you're a big, important guy on the messageboard, but guess what? The forum will go on without your witty commentary, your smarmy remarks, your endlessly recycled smilies, and the pictures you so dearly love to post when you have nothing better to say.