Is the Wikileaks 'cyberwar' actually terrorism? Of course not! It doesn't even begin to approach anything resembling a reasonable definition of the word, and it's very irresponsible to label it as such. (I'm looking at you, certain Republican politicians.) And I'm concerned when intelligent, informed liberals like Joel see the actions of Anonymous as "muddying the waters."
What is happening now is mostly (all?) simple DDOS attacks by a bunch of 4chan /b/tards. I've heard it argued that such a tactic is the 21st century equivalent of a sit-in, and I think the analogy does have some merit. All they are doing is temporarily denying access to a (virtual) location by occupying its access points (i.e. its bandwidth and/or SYN/ACK queue). The difference is one of scale and of repercussions for the activists/attackers.
I personally don't think it's a great strategy, as it is going to cause more harm to Assange and Wikileaks than it is to Visa, MC or Paypal. I can see a lot of people blaming this activity on Assange and Wikileaks, but it's clear that they do not have any role in it.
But it's NOT terrorism. Even entertaining that idea is dangerous and points us toward a world in which anyone who upsets the status quo can be tarred with the same brush as mass murderers.