I'll also be one who will mourn the loss of the physical screen lock switch when I get around to upgrading. I will add my name to the petition.
All the examples that everyone mentions seem to show how to use the software lock switch from the Home screen, which is 4 steps instead of the 1 with a physical switch.
How easy is it to lock the screen within an application, which is when I am most likely to do this? And how many steps is it then, including going back to the application afterwards? It must be more than 4.
I am guessing because of the "multitasking" you go back to the same point in the application (or game) without loss of data (or progress). Is this correct? Or does the application have to be changed to take advantage of the "multitasking"?
As there seems to be a divided opinion for the use of the switch, I think it would be sensible to have an option whether the switch is lock screen, mute system sounds and mute all sounds.