Are you talking about the in-wall/on-wall hybrid speakers (which require a rectangular hole in the wall), or the new on-wall surface mount speakers? If it's the latter, then the on-wall M22 uses this cool bracket:
You screw that into the wall in the desired location, attach the speaker wire to it, then the M22 clips onto the horizontal metal pieces. This takes care of the physical mounting and the electrical connections at once.
The on-wall VP150 uses a pair of T-brackets like this:
The VP150 has tabs on the rear that slide onto the brackets: