Sorry for the error, Gnu, the blowout preventer is still there, but minus damaged annular. I don't know what other damage may be present.

Under pressure from the White House, BP has changed its mind and will continue video during the attempt at 'top kill'. It is given a "70% chance" of working.
Top kill has worked in Saudi Arabia but has never been done on the ocean floor. The 'five-story' blowout preventer will receive the mud through tubes connected to it. See CNN description.

If the method fails, BP says another variety of containment dome will be tried. Another possibility is attaching another blowout preventer atop the non-working one.

A fisheries disaster has been declared. A statement on CNN estimates the fishing industry in the area at $2.4 billion dollars.

Hope it works.