The government twitter account hit 1,000 000 followers on Sunday afternoon.
Here’s how it was reported on the Today programme:

http://news.bbc.co.uk/player/emp/external/player.swf

And here’s how Simon Dickinson has reported the rise of twitter in the government over the last year on Puffbox:

(I’ve used a yahoo pipe to flip the reverse chronology feed from the archive page on puffbox tagged westminster+twitter so that we get the history from his first post on twitter in Westminster. Because this is an rss feed publishing inside this post it will update here as and when Simon adds posts with those tags)

[cetsEmbedRSS id='http://pipes.yahoo.com/pipes/pipe.run?_idx3dbb805ddc6e7db378a4548d6370888537x26_renderx3drssx26urlx3dhttp%3A%2F%2Fpuffbox.com%2Ftag%2Fdowningstreet%2Btwitter%26feed%3Drss2' itemcount='0' itemdate='1' itemcontent='1']