I feel sorry for EveryDNS
The Ts'n'Cs angle is just an excuse, they're really pulling the plug because he DDoS attack is threatening their business.
As to whom is suddenly pulling the DDoS attacks, that's a bit more interesting. In classic Poirot manner, let's look at whom has the means, the motive and the willinness to accomplish the act.
Sorry to all the anti-Gubbermint conspiracy theorists posting, but The Obumbler doesn't make the cut. Sure, I bet the NSA could scrape together a zombie net at short notice (if it already hasn't got one), but the Whitehouse is a bit weak on the motive and the willingness. For a start, the US has had Bradley Manning locked up for months so they've had plenty of time to go back and check what he could have been leaking. If any of it had posed a real threat to the US then they would already know about it and would have had months to DDoS Wikileaks before they actually dumped the leak. The material dumped is of nebulous value and The Obumbler always has his well-used excuse that anything in the leaks happened before he his election so it can all be blamed on the Evil Bushitler, etc, etc. So that means The Obumbler has little motive. He would also have little willingness to risk the bigger embarassment of being caught running a DDoS, which would be a career-ending action that would make Watergate look trivial.
So, if not the Big Bad Brother, whom else has Assange p*ssed off recently? Well, in amongst the other leaks is the info that just about proves the Russian Mafia are running the Kremlin, or the other way round, or that they are one and the same. The Russian Mafia do have the means and the willingness to mount a DDos attack, but I'm not so sure they'd be willing to. I could be wrong. After all, they'd have to take one of their zombie nets off pushing penis pills for a while, and that would hurt profits. And teh "bad" publicity is actually good for them - who's gonna mess with the Russian Mafia when they effectively control the FSB?
Which brings us round to my likeliest choice - script kiddies. Some "patriotic" teenager, miffed that Assange is leaking US secrets, has taken his zombie net off Google bombing his fave game site and turned it on Wikileaks and all associated with it. Script kiddies have the means, the motive (there's nothing good on the TV), and the willingness ('cos they're just too stupid to think of the consequences) to take half-an-hour to code a zombie load to whack EveryDNS. And, seeing as script kiddies are also notoriously unlikely to back down when they can see the results of their actions reported on TV ("man, I'm a faaaaaamous hax0r now!"), it is probable that Wikileaks' next DNS provider will also be hit, even if they are abroad.