I know you're not visiting the Globblog today to hear news of the London terrorist attacks, but I thought I'd give you my personal reaction nonetheless.
As regular readers know, my family and I recently returned to the US from spending four months in London (January 31 to May 31 of this year). I rode the Metropolitan Line almost every day going into the LSE or to tourist attractions in Central London from our terrace in Harrow, and from news reports it appears that not only did the first bombing occur on that line, but four of the six tube stations attacked today are on the Metropolitan.
While no one yet knows the full extent of the attack, it is certain that the London transit system will be in major disarray for many many days -- perhaps weeks -- to come. Not only was the Metropolitan Line hit, but the six stations attacked affect also the Circle, Hammersmith and City, Northern, Central, Picadilly and District lines. The murder of London commuters darkens today, and the choice of stations ensures that this attack will continue to plague London long after the victims are laid to rest. These sonsabitches knew what they were doing.
UPDATE: There appears to have been three explosions on tube trains. The structural damage to the Underground system appears to be extensive.
Here's the official word from Transport for London: "At 09:46, the London Underground was suspended and all stations commenced evacuation following incidents at: Aldgate station heading towards Liverpool Street station on the Hammersmith & City line; Russell Square station heading towards Kings Cross station on the Piccadilly line; and Edgware Road station heading towards Paddington station on the Hammersmith & City line."
Edgeware Road sounds particularly severe: "The explosion occurs at 0917 BST on an Underground train at the station. It rips through a wall and affects two further trains." This could affect up to four lines: Hammersmith & City, District, Circle and Bakerloo.
Both northbound and southbound trains were affected on the Piccadilly line near King's Cross.
I've read several reports that suggest the train near Liverpool Street was a Circle line, not a Hammersmith & City line. That being said, the Circle line shares tracks with Hammersmith & City near Liverpool Street, and the Metropolitan line will also be affected.
More information here.