It's actually Socket M, which is Socket 479 version 2.0. Socket 478 and 479 are physically similar if not identical, but wired differently. The original 479 and your Socket M are a tad different in the pinouts, too.
I have an old Pentium 4-M that is a socket 478 chip yet the socket says 479. Why? Perhaps the manufacturers were making the ZIF part of the socket for the yet-unreleased Socket 479 Pentium M Dothan a bit early?
This man is correct.
Socket 479 is a mobile socket type, Socket M is also 479 pins but, as MU said, a different pinout. If you have a newer Pentium M, Core Duo, or Core 2 Duo, you have Socket M.