From "Washington" over at Yves Smith:

Here's the scoop: BP's attempt to stop the oil spill using the "Top Kill" method has failed.

How do I know?

Well, as the New York Times notes:

BP officials, who along with government officials created the impression early in the day that the strategy was working, disclosed later that they had stopped pumping the night before when engineers saw that too much of the drilling fluid was escaping along with the oil.

Indeed, BP stopped pumping "mud" for more than 16 hours (the material gushing out of the leaking riser didn't stop during that time).

Basically, BP has failed in trying to drive enough "mud" down the well to provide enough weight to tamp down the oil gushing out. It didn't work.

Indeed, BP's "re-starting" Top Kill really means that Top Kill Version 1.0 was tried and failed, and now BP will try Top Kill Version 2.0 - adding "junk" to the mix.

Unless BP can get very lucky and plug the holes with miscellaneous junk, Top Kill 2.0 won't be any more effective than Operation Sombrero.

As the Guardian explains:

Doug Suttles, BP's chief operating officer, insisted that the operation was going to plan, but admitted: "What we do know is that we have not yet stopped the flow."

He said BP engineers would soon use additional materials to try to plug the well, suggesting heavy mud deployed so far would not work on its own.

And the Guardian's oil spill blog (a great resource which I just discovered) notes:

6pm CDT: Doug Suttles makes an appearance on CNN ....

Asked by CNN what had happened, Suttles said: "Too much of the mud is exiting the riser as opposed to going down the well bore." This could be fixed in several ways, including the infamous "junk shot", using a more viscous mud type, or finally restarting pumping at very high rates.

*
7.30pm CDT: The Washington Post has more details on BP's stop-start top kill process, and mentions that BP is considering a "junk shot" tonight:

Doug Suttles, BP's chief operating officer, said that on Wednesday the company had blasted high-pressure mud into the leaking well two times, trying to force the oil down in a procedure compared to using one firehose against another.

After doing it twice, Suttles said, the company stopped about midnight Wednesday, and spent Thursday assessing the plumes still shooting out of broken machinery. He said that company officials believed the two efforts had probably made some progress.

"I think some people believe it has. Some people believe it's less obvious it has," Suttles said. "What we do believe we've done is successfully pumped some mud, some of this drilling mud, into this wellbore."

But, Suttles said, oil was still coming out, despite these efforts: "What we do know is that we have not yet stopped the flow."

He said the company would try the procedure again Thursday evening and might add chunkier debris such as rubber balls to the mix in hopes of clogging the leaking pipe. That procedure is known as a "junk shot."

Also, see the live feed and see what you think.

There is some tiny buildup of "junk" crimping one of the jets of flow of mud or crude on top of the bent riser but that's not very significant since the BOP is the thing that really needs to be clogged and the flow through it continues unabated.

Of course, they're having to walk a fine line blowing bridging material into this crippled system because they can't put so much in that it keeps mud from entering the drilling column, since that's where they're going to have to create a true shut in with mud kill (to reverse and hold the pressure of rising crude and gas) and a cement pill (to seal it in).  My understanding is that if they seize this well at the BOP with cement they'll never be able to completely shut it in.

As of now, though, the well runs apace.

The AP article says the following: (Link)

COVINGTON, La. - BP kept pumping heavy mud into its blown-out well beneath the Gulf of Mexico on Friday, but the company's chief executive cautioned it will be two more days before anyone knows if the latest fix attempt will end the uncontrolled flow of crude that has already become the worst oil spill in U.S. history.

BP CEO Tony Hayward had projected a resolution to the so-called "top kill" as soon as Thursday afternoon, but an 18-hour delay in the injection of heavyweight mud scuttled those plans. Though engineers had stopped pumping hours earlier, BP and coast Guard officials assured the public Thursday morning that the process was going as planned.

Coast Guard Adm. Thad Allen said Friday that heavyweight mud was able to push down the oil and gas coming up at great force from underground, but it has not overwhelmed the gusher or stopped the flow.

Today Mr. Obama is in Louisiana.  Carville had suggested that if he wants to see what's really happening, he needs to stay away from Grand Isle, where BP has their concentration of workers positioned as a dog and pony show to make the cleanup effort seem more robust than it is. He needed instead to go to marsh areas, estuaries, etc. where cleanup is not occurring. Where did Obama go?  Grand Isle.  This will make for a nice photo op of success, but all you have to do is look at aerial views to see that it isn't reality.