I've only been running iOS since it GM'ed ( which wasn't too long ago) but havn't seen some of the stuff shown there. iMessages certainly do that on my 4S. The notification badge on the Applications icon is always on top. I run into the battery low notification every day and it hasn't yet disagreed between values shown at the status versus the 20% and 10% thresholds you get these alerts from.

Are these possibly from an earlier beta ?

The battery notification looks identical to that in iOS6, and probably has the same behaviour.

If you run your phone with the display off, say from 21% battery down to 11%, then it will cross the 20% reporting threshold. The next time that you unlock the phone and activate the display, you will get the notification.

It's not inconsistent; nor is it just being "optimistic" -- it may be poorly worded, but it consistently displays that same message every time you unlock the phone after the battery drains to 20%.

If the person who took that screenshot had waited another ten minutes, then the battery would probably have reached 10%, and the 10% notification would have been shown instead.

It doesn't show that message every time you unlock. Just once, after it hits 20 percent. And then again, once, after it hits 10 percent.

This is GM