For a useful rundown on what a blowout is, what causes them, how they are prevented, and how a BOP is supposed to work is covered at:

Blowout at Lodgepole1
http://www.youtube.com/watch?v=Gp9jMIXz1dg

There look to be at least five parts but the first one and the first half of the second cover the basics of what you need to know. The rest seems interesting but because I'm on a dial-up connection I haven't had time to download more than the first two segments.

The Lodgepole well is, of course, a well on land and so the BOP is right where you can get to it and it is a much simpler design than the type used on undersea rigs. But many of the basics are similar in design and function.

I selected the Stupak release because it brought many of the pieces together in one spot. Most of the substance in the release was testimony from people in the oil, and oil services, businesses. While Syupak is certainly a politician the piece is made up mostly of simple statements of fact that are believed to be true. The proportion of political content seems to me to be quite low.

All of these articles many of the same sources and quotes but they also add a bit. The NYT a bit more than the other two.

http://www.nytimes.com/2010/05/11/us/11hearings.html?pagewanted=2&fta=y

http://www2.wsav.com/sav/ap_exchange/nat...rs-find/123166/

http://www.theindychannel.com/news/23526647/detail.html