I've had my mac mini with the Apple bluetooth keyboard for several months now, and I've finally found the hash key (#) - it's at Alt+3 and not the usual Shift+3 like it is on all other UK keyboards. It's not marked on the keyboard - hence the difficulty. I've been working round this by using my own keyboard layout. Think I'll stick with the alternate layout as the @ and the " have been switched too. Old habits die hard, especially when I use a normal UK layout at work.