We've just a launched some new features for Google Docs presentations:

Multi-shape formatting - after selecting multiple shapes, you can change fill color, outline color and border weight for all of the selected shapes at the same time.

Multi-text box formatting - you can now change the formatting of text in all selected text boxes at the same time. (To select multiple objects, hold down the Shift key while you click each object, or drag over all of the objects you'd like to select.)

Vertical alignment of text - to align text to the top, middle, or bottom of your text box, enter text into your presentation and click the 'Text vertical alignment' button in your presentations toolbar (directly to the left of the 'clear formatting' button)

-Steve