Search Twitter for the phrase "Right, off to the gym and to listen to the Packetpushers Openflow podcast"
I'll wait.
Note the large number of results, at least as of May 22, 2011. Apparently Twitter is just chock-full of exercise nuts who listen to techie networking content while working out. Yet, its odd that all of them use the exact same phrase. It is also odd that a couple accounts use the same photo.
Of course, its not odd at all: these are all bots. Twitter bots started out very simple, harvesting a random selection of tweets from the stream and using them as their own. They've evolved and become more believable, harvesting tweets of a particular theme. In this case, they selected tweets via exercise-related keywords like "gym" and "workout." That they happened to pick up a highly unusual topic is just dumb luck.
If you examine the tweetstream of any individual bot, its quite believable. They come across as an exercise-obsessed but otherwise normal person. The machine algorithms still fall prey to silly things like a tweet about getting up in the morning followed shortly thereafter by going to bed, but on the whole this crop of bots has advanced considerably since the last time I looked into it. The game is definitely afoot.
One final note: the podcast these bots mention is Packetpushers show 40, and if you are interested in techie networking content it is a good one to listen to. Perhaps you can listen while working out.