How to rotate text in numbers? EASY.
Very EASILY. In numbers 5.0, create a new text box. Under "Format", choose "Arrange". Near the bottom of the menu is "Rotate". Pick your angle. I'm not sure why there are so many dead threads saying this isn't possible. I"m sure at one point it wasn't, but it is now. And it's easy.
MacBook Pro, OS X Mountain Lion (10.8.2)