My $0.02 <disclaimer> I don't use twitter (I have an account, but never tweet, almost never look at the people who I am following) - so maybe I am too old school to have anything interesting to say. </disclaimer>

This strikes me as severely reducing the S/N of the social networking space - if this gets popular, which I assume is your goal, then a large percentage of tweets will be generated automatically. Now permutate this machine-generated "social" information with all the tools springing up to analyze tweets and derive all kinds of useful crowd-sourced insights. It all becomes that much more diluted with less and less information actually created by a live, thinking human being. This might be the start of a trend - tools which tweet automatically based on incoming tweets, creating that feared endless loop which you cannot detect because you only control one participant. Oops, some kids are out trampling on my lawn, gotta go.