The title says it all. James Cameron has joined Twitter on January 28.
For those who are interested: His user account is @JimCameron.
According to Hollywoodreporter, Cameron also receives the International 3D Society's first Harold Lloyd Award for 3D achievement today. The award ceremony will be recorded and telecast in 3D as part of a two hour special on 3net. Last year, Avatar already received 7 awards from the society, which are listed here.