Justin Bieber has become the second person on Twitter to earn 12 million followers, leaving him behind only Lady Gaga in the battle for social networking supremacy.

Bieber's followers made "CONGRATS JUSTIN" a trending topic on the site today as the 17-year-old singer eclipsed the 12 million mark. His fans have been showing their love in a number of ways lately, by making "Derek Bieber" a trending topic on Twitter, helping him win four Teen Choice Awards, and even by (apparently) stealing a street sign bearing his name.

With more than 10,000 tweets since joining Facebook more than two years ago, Bieber is a much more active tweeter than Gaga, who has posted just over 1,000 times in three-plus years on the site. Can Bieber catch the 'Born This Way' singer, who currently boasts 12.8 million followers? Given the power of his Beliebers, the answer is probably 'Never Say Never!'

Bieber's latest tweets have all focused on producer Tricky Stewart, who helped Bieber write and produce the smash hit 'Baby.' Bieber and Stewart are back in the studio working on another potential hit song.

Interestingly, on the list of the most popular Facebook fan pages, Bieber is only in 10th place overall and sixth among musicians -- trailing Eminem, Rihanna, Gaga, Michael Jackson and Shakira.