I also wonder if they could work with a recognized non-profit in order to make gifts tax-deductible (e.g. give them money to EFF, then EFF funds wikileaks).
If you're asking for this kind of contribution then you need to be 100% transparent.
First, it's the way they ask for donations. They close the website and it's almost like "If you want Wikileaks, you have to pay". I don't think this helps their cause in any way. I remember seeing a banner while the website was still live, but that didn't last long.
Also, I don't think they reached a point where then can't hold the website online. It's not like it's new.
Like someone else said, they don't tell what their expenses are, nor how much money they need.
On the technical side, I don't see the need for having MediaWiki running. It's not the most lightweight application, and since most of the publications are done by the team behind the project, maybe having an approach like http://cryptome.org/ would make it less CPU hungry and would not depend on so many resources.
Since someone mentioned the mirror on Freenet, here is the mirror on the Onion land: http://gaddbiwdftapglkq.onion/
It would be helpful to know what are they looking for - and whether we can contribute, with our specific skillset
Also varnish cache would help.
I image most of their readers reach wikileaks are direct from blogs, news articles, etc.
I doubt I'm the only person on HN who has large amounts of computing resources to spare. I suppose we'll see what's required to help.