Actually it's more Wish you were here that is an ode to Syd. The theme of Dark side was exploring what can cause madness (Time, Money, Death (great gig in the sky), Brain Damage, etc.), and on WYWH, well, I hear Shine on you crazy diamond like a song complaining Syd's tragic end and on the actual song Wish you were here you can really hear Water's longing for Syd.
Well, my interpretation. Floyd rules.
~~Phunkin Phatt Phreerider~~