Milkshake is a pretty good guess but I think maybe it stands for Marshmallow.
Also I gotta say I really like the now cards that can be pulled up on any screen. I don't care if that seems creepy or whatever, but its really cool. I have a feeling that I'd forget to use it a lot but nevertheless the option to almost instantly be able to pull up info on a certain place or thing is really nifty, hats off to Google on that one. And the app drawer does seem kinda ugly but hopefully when its fully released they give you options in the settings to be able to switch it back or customize it to how you want it to look.