Brown was, at times, referred to as the spokesperson for Anonymous. He wasn't. There is no spokesperson for Anonymous. The lack of structure makes such a claim ridiculous but bureaucracies are limited to imagining they are a reflection of the entire world.
You can find the story here, his pre-sentencing statement here and a statement from the Electronic Frontier Foundation here.
I strongly recommend reading his statement.
He will also have to pay $890,250 restitution to Stratfor and other companies as if Brown himself hacked the companies. There's also $225 in fines.
From the Guardian link:
In his statement following the judge’s ruling, Brown struck a different tone. “For the next 35 months,” he said, “I’ll be provided with free food, clothes and housing as I seek to expose wrondgoing [sic] by Bureau of Prisons officials and staff and otherwise report on news and culture in the world’s greatest prison system.”
I wish him well on his new assignment.