They used the <canvas> HTML5 along with the API streaming Twitter to create the map above. The map shows which regions of the planet contains Twitter users posting at the last minute. You can choose to display a smoke or heat map, plus the map also offer a 3D stereo option (the one who needs glasses with blue and red lens)
For now the World of Tweets only counts tweets of people who activated the geolocation function in your profile settings. That is, only those tweets with “From [city here]” are shown, as there is no way to find out where other posts left. According to statistics on the site, Brazil accounted for 6% of the more than 1.4 million tweets recorded since the beginning of the month.
The site does not have much use beyond display a graphic kinda cool. But also it has the potential to be a huge time sucker, so if you have attention deficit disorder is better not enter the… look, a blue drop on the map … cool…