Today has certainly been a significant day for ‘hacktivism’, or hacking to create awareness and activism, and “a new era has come”, according to Anonymous, which has been busy avenging the US Department of Justice’s (DoJ) decision to bring down filing-sharing site Megaupload.

In response to the Megaupload decision, the hackers introduced Operation Megaupload, a move that saw it bring down the DoJ’s website, and a number of other sites including: justice.gov, universalmusic.com, riaa.org, mpaa.org, copyright.gov, hadopi.fr, wmg.com, bmi.com and fbi.gov.

The collective clarified its targets in an announcement posted to Pastebin, under the ‘OpMegaupload’ alias, which clarified that it was acting in response to the decision on Megaupload.

We Anonymous are launching our largest attack ever on government and music industry sites. Lulz. The FBI didn’t think they would get away with this did they? They should have expected us.

A video published to YouTube — “Don’t Mess With Us” — heralds the action as the beginning of “a new era”, explaining that “this is a time of action, as a nation we might come together and fight the tyrants”.

The DoJ called the moveone of its largest ever in a statement that appeared to be issued as an example to halt future copyright infringement on the Internet:

This action is among the largest criminal copyright cases ever brought by the United States and directly targets the misuse of a public content storage and distribution site to commit and facilitate intellectual property crime.

However, the organisation had reckoned on Anonymous bringing its website down along with a host of other sites. Megaupload itself has regrouped and is looking to relaunch a site outside of the US, and away American jurisdictional.

Earlier this week, it was reported that Anonymous is planning a major raid on Sony, with the aim of placing torrents on its homepage and making all content in its online store free of charge. Given the events of today, Sony must be feeling the pressure ahead of Monday, when the rumoured attack is scheduled to take place.

The fact that the government and other firms were so easily breeched is likely to set alarm bells out across the world, particularly amongst corporate companies that supported SOPA publicly at any point.