My observation of #Torchwood took place on 1st November 2009. I tracked tweets from 00.01am to 23.59pm using Twapper Keeper and I have used screen shots of these Tweets to create a chronological slideshow (see below - this may take a few minutes to load, if you can't get it to work after a minute or two try the Flickr version).
The record of all Tweets on #Torchwood can now be found on Twapper Keeper including comments made since I started looking at the hashtag as a possible ethnographic site (up to and including current incoming Tweets).