According to the Daily Mail article, a computer-generated image of what Washington DC would look like after a nuclear attack was recently posted on an Islamic extremist website. Simultaneously, there have been rumors circulating suggesting that "the FBI was warning that an Al Qaeda video was about to be released urging militants to use weapons of mass destruction to attack the West."
Turns out that the FBI hasn't issued such a warning. Nor is the picture of Washington in ruins an Al-Qaeda creation. It's actually a piece of concept art that was used to promote the game Fallout 3, from Bethesda Softworks. Shacknews.com reports:
The artwork was released as part of Bethesda's early promotional campaigns for Fallout 3, which takes place in and around the Washington, D.C. area decades after a nuclear catastrophe. The image appeared on the Daily Mail's website under the headline "Al-Qaeda's terrifying vision of a devastated America in the wake of a nuclear attack."...
The image also appeared on the Australian news outlet News.com.au, citing terror watchdog organization SITE Intel as having released the image "which reportedly appeared on an Islamist forum."
Though several members of the press have since pointed out the gaffe, neither the Daily Mail nor News.com.au have updated their stories with corrections or retractions of the claim.
What occurs to me, when I look at the picture, is how unlikely it is that the Capitol Building would survive a nuclear attack. Growing up in DC, I always heard that the one building in the city most likely to survive a nuclear bomb would be the National Cathedral since its walls are massively thick.