I just spent a minute scanning my dock for messages on the Mac. I realised I have been missing it because it is blue and I was looking for something green.
It does seem odd for this dichotomy.Why is messages on the Mac blue and not green.
I’m guessing its the history of the application on both platforms. iMessage is the successor to iChat and a quick wikipedia search shows that iChat was a blue icon where as messages was always green on the iPhone.
The other thing is I wonder if it originally because Messages on the Mac could only chat over iMessage so it had the blue bubbles only and then being able to receive SMS text was a later feature.