This frame grab of the PBS Web site shows a screen that appeared Monday. (AP)

According to the group’s very active Twitter, the hack was retribution for the “Wikisecrets” episode of Frontline. The group tweeted @WikiLeaks, “We hope our hacking gave Bradley Manning a smile. That man deserves something nice,” referring to the U.S. soldier who allegedly leaked restricted materials to the organization.

Whirlpool, a member of LulzSec, confirmed the hack’s motive to Forbes Tuesday over Instant Message chat, saying that the documentary “painted a negative picture on WikiLeaks.” The hacker said he originally planned to “write about Obama choking to death on a marshmallow, but ... figured Tupac would be funnier.”

PBS is still having some trouble with their site, and has moved their homepage to Tumblr during the outage. LulzSec, meanwhile, seems to have started a new hack — this time on the Sony Web sites again.

LulzSec said on Twitter they are currently rolling out the next phase of “Sownage” — that’s Sony plus the word ownage — taunting the company with tweets including, “Hey @Sony, you know we're making off with a bunch of your internal stuff right now and you haven't even noticed? Slow and steady, guys.” They already claimed responsibility for an earlier hack on Sony music site in Japan.

The group is apparently not responsible for the massive breach on and the PlayStation Network, which possibly left about 70 million users’ credit card information vulnerable. But it did take credit for leaking the e-mail usernames and passwords of Fox Broadcasting employees and the names, e-mails and phone numbers of contestants from the upcoming American version of “The X Factor.”

As blogger Zennie62 pointed out, it appears that AT&T may be the group’s next target. This prediction comes courtesy of a May 17 tweet: “AT&T aren’t going to enjoy what The Lulz Boat is cooking.” But it doesn’t seem the group will stop there: “We’re hard at work. Multiple targets, vast lulz possibilities.”

This year alone, several high profile companies have been hacked. When Wikileaks’s founder Julian Assange was arrested in December, Operation Payback, launched by Anonymous, hacked the Web sites of MasterCard, Visa and Paypal. The group leaked e-mails from a Bank of America employee in March.

So are all the LulzSec’s hacks done for a specific purpose, like the one on PBS? It doesn’t seem so.Whirlpool told Forbes the group’s “main goal is to spread entertainment,” with the PBS hack done partly for “lulz.” On question-and-answer Web site, Formspring, the group said their “goal is to spread fun, fun, fun!”