Hacking has a long and variably honoured history. The first hackers to bear the name, a group at the Massachusetts Institute of Technology whose exploits were recounted in Steven Levy's 1984 book Hackers, were dedicated to building things. Subverting rules, to be sure, but a 'great hack' meant above all else cleverness and, the ultimate accolade, elegance.
Some of the best hacks were student pranks — MIT has an online gallery of the best of these, though my favourite actually happened at Cornell, where in 1997 someone whose identity is still unknown managed to impale a giant pumpkin on the spire of the clock tower using methods that have never been fully understood.
The discovery in 1980 that the licensing restrictions attached to the latest version of a printer at MIT's artificial intelligence lab launched Richard Stallman's lifetime career of writing and campaigning for free — as in free speech — software. It was arguably at that moment that 'hacking' developed its political edge.
The identification of 'hacking' with cracking into other people's computers developed through the 1980s. Many of the old-style hackers resent being conflated with crackers even now, but their exclusive rights to what was a badge of honour have pretty much been lost. To the general public, a 'hacker' is someone who breaks into other people's computers.
By the early 1990s, 'hacker' had come to mean what it still means to many people: a very clever, computer-obsessed, (usually) young, (usually) male with maybe a shaky grasp on the ethics
The WikiLeakers fit reasonably well within the tradition of the hacker as freedom-of-information activist. No one has alleged that they cracked into anyone's system illegally in order to obtain the documents they publish. They are closer to journalists than to hackers.
Those mounting the DDoS attacks on companies such as MasterCard, Paypal, and Amazon, may style themselves 'hacktivists', but it's hard to see how they merit the term. Yes, they are protesting actions they believe to be unfair, even morally bankrupt. But they aren't building anything or opening sealed boxes to show us things that should never have been kept secret. If I were an old-school hacker, I'd be out looking for a new name for myself.