Here's a guy who seems to know what he's talking about (but I have no idea) who analyzes the well design, does an analysis and seems pretty sure that the well was seriously underdesigned and pretty much guaranteed to fail. Scroll down to post 2262. (Not a typo.)
In other words, due to the way this well was designed to be hung off, it was designed to have a blowut in the production casing by intermediate annulus or at the very least have severe casing problems.
This combined with the substandard cement job with nitrogen injected cement was the single most improtant contributing factor to this occurance.
Even grimmer news is reported on this website, which states that a Russian deepsea team in a deep submergence vehicle surveyed the sea floor around the well and found that the seabed has fractured and oil is leaking out from at least 18 other sites. There seems to be no other mention of the Russian team working with BP that I could find, so take the report as you will. However, a huge underwater plume with heavy, thick, dark oil was found by a Louisiana team of scientists. I had heard about various plumes in the media, as well as various seabed leaks but with some suggestion that these leaks were natural. Now, I doubt it.
As further proof that the BP well blowout fractured the sea floor, there's this:
Today Matt Simmons, one of the largest investment bankers in the energy industry appeared on Bloomberg. The chairman of Simmons & Co. INTL went on to explain that there is much more to the oil leak than the news has been reporting. Last Sunday, NOAA confirmed reports of a second fissure about 5-7 miles from the original. This new fissure appears to be releasing a plume the size of Delaware and Maryland combined! He went on to state that “the plume from the riser is minor thing… the best estimate is about 120,000 barrels of oil per day”.Found here. More info on Matt Simmons.
For what it's worth, lots of reasonable people think Matt Simmons is a kook, and the above website posting about Russia also looks pretty kooky.
Here's another interesting link, found by commenter GreenFloyd at theoildrum.com. In it, the team that set up the Graphic Information System (GIS) for this disaster explains how they were fired; all of the GIS information collected by various US agencies such as the Coast Guard (your tax dollars at work) is now being sent directly to BP, never to be seen again. How are they getting away with this? It's pretty clear we're not the boss of them.