A general principle to keep in mind when dealing with hackers is: If a gang of hackers announces the exact date, time and targets of an upcoming hack, it is not going to happen. So we'd bet 800 bitcoins that this attack on "46 major companies around the world" planned for 4pm today by a hacking group associated with Anonymous is not going to come off.
The campaign, announced last month, is called "Operation NewSon," which sounds more like a 90s alternative rock album than a hacking spree, but whatever. A group called the Wikiboat is threatening to take down the websites of companies like Apple, Bank of America and Toyota and leak sensitive data. The FBI is taking it seriously enough to apparently send out an email to some of the companies targeted. But then the FBI also spent months entrapping a bunch of idiot anarchists so their risk-calculations should be viewed skeptically.
And another thing: Who plans anything for 4pm the Friday before Memorial Day?