Does this circuit regulate current?
It is a current limiter, and the current limit is set by the 12 ohm resistor.  The idea is that when enough current flows through that resistor, Q2 is turned on, pulling down the base of Q1, "strangling" it.

If Q2 turns on with a Vbe of, say, 0.7V, then the current is limited to 0.7V/12ohms = 58mA.

To understand it, first imagine that Q2 is not there.  Basically Q1 is turned on via its base resistor and lets through as much current as it can.  If only there was 'something' that would start turning it off when current reaches a settable amount... and that's where Q2 comes in, and the 12ohm resistor is really a current sensing resistor.