Google Presentations now supports slide dragging to reorder slides, and right clicks to change slide background and to duplicate slides.

Editions impacted:
Standard, Premier, Education and Partner Editions

Languages impacted:
US English

How to access what's new:
Sign in to Google Docs, open a presentation, and try these new editing options.

For more information:
http://www.google.com/a/help/intl/en/users/dands.html