Basically, a famous person can write anything and it will be retweeted. An unknown person can write the same tweet and it will be ignored.
Link to paper:
Sasa Petrovic, Miles Osborne and Victor Lavrenko. RT to win! Predicting Message Propagation in Twitter. ICWSM, Barcelona, Spain. July 2011. http://homepages.inf.ed.ac.uk/...
And I will claim this as a fake first post. #slashdot
There are simple ways to stop this. Whether Twitter does this is another matter.
This is the same as any other optimisation task (eg link farms for Page Rank). People will try ti and (eventually) Twitter will work-out how to clamp-down on it.
Rinse and repeat.
Why is this news?
Take an astronaut to launch.