It took some time to be certain that terror was the basis since the initial reports stated that explosions in the London Underground were caused by power surges. But at this point, with multiple Underground explosions and bus explosions there can no longer be any doubt that this is a well synchronized terror strike against London.  Beyond that, little is apparent.

Personally, if I had to ride a bus or train in a major metropolitan city in the U.S. this morning I'd be very wary. Let's hope there isn't a strike here.  I don't remember which general said it but I don't think there'd be much of a Constitution left if there is terror strike here.

Initially I saw the report on BBC News.
http://news.bbc.co.uk/2/hi/uk_news/default.stm

I then tried to follow the updates via News Now, but that seems to be down at this point.
http://www.newsnow.co.uk/newsfeed/?name=Current+Affairs

Surprisingly on News Now there was a link to a blog that had some "street" info.
http://europhobia.blogspot.com/2005/07/london-tube-explosions.htm
l#comments

Other UK sites I've been following -
http://www.sky.com/skynews/uknews
http://u.tv/newsroom/