Thought it couldn't be done? Apparently, Dell have had some success with their Twitter feed and report they made one million dollars through Twitter. That's not a huge amount of cash for Dell, but its a glimmer of hope that there some viable business models for Twitter and, more importantly, the consumer market might be ready for them.
Looking at the followers on Twitter for Dell tweets, there seem to be about 4,000 followers on channels that advertise products. This means that each follower was worth approximately $250 in 2008. Given that a big majority of the followers would not have made purchases, lets say only %10 actually buy something (and that's probably generous). This means each purchase would have averaged out at $2,500. That seems a little high for the average Dell purchase... So maybe you can't make a $1 million on Twitter just yet, but the target is set for next year.