The Presidential Palace and the Cathedral -- two iconic buildings in Pòtoprens -- are both destroyed.
The MINUSTAH (UN stabilization mission) headquarters has collapsed, and the diplomat in charge of the UN mission, Hedi Annabi, is now dead. I'm no fan of MINUSTAH, but obviously this is a tragedy.
One of MSF's facilities in Haiti has been toppled.
Richard Morse, the owner of the Oloffson, is apparently twittering fairly regularly.
Edit: New York Times slideshow.