I've been a little hesitant to post anything about the Deepwater Horizon/Macondo Blowout. I tend to work on things from the Christmas tree up, but here are a few things to peruse for starters:
The Oil Drum has had some fantastic coverage of the blowout. Probably the best single website when it comes to clear, concise, timely, technically accurate coverage (although RigZone has been pretty good, too).
P.E. writes about about working on rigs and pulls from his vast experience to offer his thoughts.
In the end, the document that should be the most read is the Coast Guard/MMS Board of Inquiry findings. Here's the one for the Ocean Ranger [PDF]. While we can make some very good hypothesis about the technical causes of the blowout and what could be done better to protect the environment and personnel, remember to keep an open mind until all the data is in, especially when the Blowout Preventer is pulled and carefully analyzed on the surface.
60 Minutes. The 60 Minutes piece on the Deepwater Horizon is well worth a watch. It fills in a few holes, but remember it's just a few pieces in the giant puzzle of what went wrong (and for a disaster of this magnitude, there's many, overlapping modes of failure).
Here's a couple of my old posts worth a read, too:
Engineering Disasters: The Demise of the Ocean Ranger
The Offshore Imperative
UPDATE- MMS engineer warned of the danger of deepwater blowouts in 2009. Note that the odds of a deepwater blowout were calculated to be roughly 1 in 400 chance; that's about the same as a Category 5 hurricane destroying our crappy 100-year-level storm protection...
Oil Reaches Shore - Boston.com's Big Picture