WikiLeaks is a website dedicated to releasing leaked information. It isn't doing anything new, leaked information has been a large part of Journalism for a while, but what is different that the leaks are delivered in an almost no edited format.
Recently WikiLeaks got hold of 251,287 leaked US Embassy Cables. These are short reports about all manor of things. I found the report on colonel Gaddafi rather interesting, but there has been a lot of criticism towards the leaks; mainly around the possibility that they would harm diplomatic relations and cost lives. Reading the reports you can see many of the names have been removed, so I am not convinced by the loss of life argument, but there was a TED talk earlier in the year with WikiLeak found Julian Assange giving his account on why WikiLeaks is a force for good.
WikiLeaks is under (government?) attack, so has several Mirror Sites setup.