Memory cleaner has been included in most OS's for quite some time. It works in conjuction with Content Protection. All Memory Cleaner does is scrub the already free memory so that old data can't be recovered from it. As with most memory the memory isn't really deleted when no longer in use. It's just marked as writable again. So, theoretically, someone could disassemble the device and read what was "deleted" from the device. The Memory Cleaner actually writes over it again so that the deleted info can't be read, ever.
Haven't tried just pressing K (w/ dial from homescreen NO) or alt-enter?
K is a speed dial but alt-enter might work but with the theme I use my bb is not normally on the home screen. I noticed when it doesn't lock is when the red light keeps blinking but I can't figure out how to stop that either.
Or you could just put it on stand-by too by pressing and holding the mute button for 2secs. If you want to take it out of slumber mode, you can just mildly-tap the mute button again.