Wikileaks is not the media. They are a broker, a middleman. The have negotiated exclusive access to leaked data, rather than just posting it for anyone to download. There are rumors about them buying and selling leaked data. There may be quid-pro-quo for exclusive access to information in returns for donations to Wikileaks.
Google "john young wikileaks".
If they are a buying and selling classified documents that is a crime worthy of prosecuting to the maximum extent of the law. What I had heard and assumed (not a good excuse for me) was that they were posting the information for people to read for free. I have gone to some websites (mostly press) and seen some of the non-classified dispatches, that would just "confidential." In those cases there was no cost for reading anything and they were mostly no big deal from what i could see, but I didn't read many nor did I read anything that was identified as classified.