Somehow I agree with Gilrandir, but I don't think it is just a smokescreen.

In taking part actively in Syria, Putin obliged other countries to determine their policies in conjunction with his. He regained (or gained) the centre point in negotiation and obliged USA to reconsider their stance.
He gave the signal to USA that they are not any more free to bomb, he can do it as well.
Considering there is a meeting today about Ukraine, he will have some political advantage in showing how he has the capacity to intervene.
He showed to CIA that he can hit their "protégés", even better he showed CIA's "protégés" they are not any more out of target.

Now, former USSR was supporting Kurdish fighters in the 50-60's. I don't know if this will or have an impact on Putin's political/geo-strategical decisions.