UI animation?

What can I do to animate 2d graphics, like menu systems on the iphone using untiy?

GUIManager, SpriteUI, SM2 etc. Do a forum search and you will find a ton of options.

Whats the best one?

None are the “best”. They are all very good and useful. Try them out and see which one suits you. I also just released a simple GUI/HUD library yesterday that is very easy to use:

http://forum.unity3d.com/viewtopic.php?t=41343&highlight=