OSX Mavericks: iMessages Bubble Color?

Hey guys!

Just downloaded OSX Mavericks and gotta love it! I have one question, my iMessages now has a bunch of different colors for every individual? Is this new? Will this be added to the iPhones, iPads, etc.? And if this is "normal" can we customize these colors for different contacts? And how would we do this?

Keep up the great work!!

Thanks!!