I've been waiting a looooong time for this one. Here it is, the first photo of Obama at the Oval Office desk:

"(E)specially interesting because it's clear he's instituted a new dress code: The new president is not wearing a suit jacket. It was a rule during the Bush administration that no one ever enter the Oval Office without a jacket."

From a link at:

http://politicalwire.com/archives/2009/01/21/change_comes_to_the_oval_office.html

Unfortunately, there's no photo credit. I can't recall who the official Obama photographer is, anyone out there remember?