Not going to say much, go read real news.
My feeds have been very quiet so far, only the professional media have any news - so much for citizen journalism replacing the established media.
Initial count was 2 dead; latest reports suggest 50+, highest figure I've seen is 90. On the basis of this so far, it's slightly tempting to say that it's a fairly weak terrorist act - except, of course, that the aim of a terrorist act is not to kill people - it's to cause terror. That bit seems to be fairly affective - not much "terror" per se, but a lot of uncertainty and doubt.
My condolences to all those affected in any way by these events, but especially those affected by any fatalities there may be.
I plead with the people of the United Kingdom: by all means, a swift, strong response to cowardly bullying such as this is warranted. But please, please, be careful - if you over-react, if you allow too many of your freedoms and civil liberties to be taken away, if you allow paranoia to take hold, if you give in to fear - whoever is behind this has won. Don't stoop to their level.