Now, as I am not White House photographer Pete Souza, it's pretty clear that I didn't take this photo. However, the photo on the White House Flickr stream carries the "U.S. Government Work" license (that is to say, it's public domain), though the photo description has an additional disclaimer that says as an official White House photo, it should not be used in a way that "suggests approval or endorsement of the President, the First Family, or the White House." In either case, we're cool.
(As a reminder, I saw the photo in a GovExec story, and submitted it to Fark with a headline, "Photo surfaces of President Obama refusing to shake the hand of a disabled janitor," which still makes me giggle.)
Looking around regular Google and Google Image search, I did find a few other recent photos being used (and properly attributed, thanks). Here are some (not including a bunch that show up in spam blogs):
[Update: Although I mentioned proper attribution, I forgot to explicitly mention that nearly all of my Flickr photos are licensed under Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0), which means that as long as people attribute the photo and flow the license down to any derivative works, they can use it, even for commercial purposes. However, other things, like model rights, still apply.]
Here's my friend Dave, illustrating grill mastery in a blog entry, The Man’s Guide to Grilling (that Every Woman Should Know)