Time Magazine can tell you. But so can I. (Was that 140 characters or less?)
There are two reasons Twitter is popular in Brazil. One is that as more and more people in up-and-coming countries get online, the Internet becomes democratic, giving everyone access to the same content. Said content can be extremely interesting or, as in most cases, it can leave you like a dog chasing its tail, filling your mind with one-thousand bytes of useless information (at which point you may wish to ask yourself what conclusions about life would you be coming to had you not spent that hour reading nonsense).
Reason two is that Brazil has a celebrity culture, much like the U.S. and Twitter gives ‘normal’ people the chance to connect with ‘special’ people who are one of the following: beautiful, powerful, young, or rich. In fact, this is a huge turn-off for getting me to take the service seriously because for every interesting news article on Brazil listed on Twitter, there are hundreds upon hundreds of Brazilian teen girls tweeting to and about Justin Bieber, Kaká, Beyonce, you-name-it.
Interesting what happens when you look into the etymology of the word ‘tweet’, as individual messages on Twitter are called. The word ‘tweet’ originated in the year 1845 and is imitative of the sound made by a small or young bird. If you were to follow that logic, that means users are either small (unimportant) or young (not mature), enjoy imitating non-original ideas in 140 characters (linguistic minimalism, no way to convey things in depth) and like to ‘follow’ people on stages/altars (actors, politicians or clergy…not that there are clergymen on Twitter).
Just a thought. Here are a few more by Time.