I've stumbled across this in my own compositions and I'm sure I've heard songs on the radio do this.
The simplest way to describe this is to take a regular piano and paint the keys so that there's only sets of 2 black keys (instead of the usual 2 black and then 3 black) so that the notes in the scale would be something like:
A B C D E F G A Bb C D Eb F G Ab Bb C Db Eb F Gb Ab Bb B C#
Or painted onto the current piano setup:
It's like a "mini" scale that follows the pattern of tone semi-tone tone, and repeats indefinitely.
I find that it works well when you don't change positions quickly, because I guess your ear "forgets" what scale it's in.
Is there an official name for this and has anyone else come across it?