I upgraded my firmware to 4.2.1, but found that all my apps still run OK. Only funny thing is that the so-called mute switch at the top right doesn't lock the screen rotation like most manuals/guide books say it would. It just mutes the sound. Any reason?

I feel still okay for the changes, but anyway, rumors says that in iOS4.3 it might let us to choose the switch for screen rotation or mute function. So, we might wait and see.

What are the extra steps to lock the screen? I tried looking under settings but can't find any.

press power button once?

Thanks man, haha I thought that button was some kind of repeat button for the ipod. Cheers!