It wasn’t long ago that actor Ashton Kutcher and CNN were racing to be the first to 1 million followers on Twitter. Now Ashton is closing in on 5 million and is still atop the list while CNN is currenty #11 with just over 3 million followers. But just how influential is a tweet?

Or more importantly what would you pay to have Ashton tweet about your business or website. There are some markets developing now to let supply and demand tell us a little more about the value of a tweet and Twitter has just announced a new ad platform that will shed some light on Twitter’s influence although it will take a while for these to launch and get enough data for the market to clean up the noise. Ad.ly offers a market whereby Twitter users can sell a tweet and set the price for that tweet. Unfortunately Ashton is not on ad.ly so we can’t find out what he is selling a tweet for but some relatively big named Twitter users are on ad.ly. NBA star Paul Pierce will tweet to his 1.5 million followers for $5734 and actress Mandy Moore to her 1.9 million followers for $2800. I did an experiment spending $30 on ad.ly to have Twitter user, macTweeter, an ad.ly member, tweet about TweetAlarm to its 106,000+ followers. The tweet yielded 305 clicks at a CPC of just under 10 cents. I didn’t try different times of day, a variety of users or varied content, just 1 simple tweet to promote a web site. Certainly interesting results although not statistically meaningful. Also of note, Bill Gross, founder of idealab, has recently launched Tweetup an adsense like service for Twitter so as that grows we may be able to get some additional data on the market value of a tweet.

While Ashton doesn’t use ad.ly and as far as I know doesn’t sell tweets, he does use the bit.ly URL shortening service in many of his posts on Twitter. With the bit.ly API and a little bit of PHP code I was able to look at Ashton’s recent tweets that included bit.ly URLs. The sample set was small about 20 tweets in total and the average click through was around 18,000 clicks.

Not to snub 18,000 clicks but given the short lifespan of a tweet and the fact that many people sign up and follow lots of people but don’t then use twitter on a regular basis, an Ashton tweet isn’t as influential as I would have guessed. With nearly 5 million followers that is about 0.4% click through. Well that is a nice spike and might certainly start a snowball it won’t bring down servers like a TechCrunch mention can (hint hint).