On the same day Jeff Stein reports the same story for Newsweek. There are some differences in the details.

Mughniyah died from a tire blowout on a spare tire. The tire was filled with C4 explosives and metal balls and exploded at the back of a Toyota 4wd when Mughniyah walked past.

So far it had been assumed that the assassination had been a Mossad plot but the "news" in the story, based on "former U.S. intelligence officials", is that the CIA was heavily involved and that Bush gave the order to kill Mughniyah.

Two Israeli reporters, sometimes disseminators for Mossad phantasies, add some not so important bits.

The main difference between the two main stories, important in its legal aspect, is in who pressed the button. The Washington Post version:

The device was triggered remotely from Tel Aviv by agents with Mossad, the Israeli foreign intelligence service, who were in communication with the operatives on the ground in Damascus. “The way it was set up, the U.S. could object and call it off, but it could not execute,” said a former U.S. intelligence official.

The Newsweek version:

The kill was made all the harder by the way the bomb would be detonated. There was a two-second delay from the time the CIA and Mossad agents in the lookout post pushed the button to when the bomb exploded. Under the plan, the Mossad agent would ID Mugniyah, and the CIA man would press the remote control.
...
Finally, on the night of February 12, 2008, after two months of round-the-clock surveillance, they caught Mugniyah alone.

“They made a positive ID. Click. One, one thousand; two, one thousand...ka-boom.

So in the Neweek version some CIA guy is guilty of murder while in the Washington Post version somebody in Tel Aviv should be hanged for it.

According to Elijah J. Magnier, who in 2008 reported the story from the Syrian side, the Newsweek version is the more correct one. Magnier also had some additional details in his tweets today.

But aside from the content of the story, which I do not believe to be really relevant, there are questions that could need some answers:

Why is the Washington Post "dumping" the story into the Friday evening/Saturday morning news hole? Usually such a story would be published Saturday evening/Sunday morning thereby and fetch some time on the Sunday shows.

Why is the story coming out now? Has it to do with the spat between Obama and Netanyahoo? Is it a diversion from Israel's recent loss against Hizbullah? Has it to do with the U.S. negotiations with Iran?

The story was obviously ready for some time to be put out by two competing papers. Both were likely waiting for a go from their sources to publish it. Why was the "go" given now? By whom?