Not to sure about the name but I'm really liking the new features especially Messages
http://www.apple.com/macosx/mountain-lion/features.html#messages
Would like the labels I've set next to the name for same contact multiple numbers, easier to see what's what although there is the speech symbol to tell me it's their Message number.
I like the idea that they have split everything into separate apps, notes on its on not in Mail etc.