Wikileaks Founder Julian Assange Has Nothing to Fear from the CIA or FBI

On the other hand, he would be worried about finding Polonium in his coffee, courtesy of the Russian FSB:

Yesterday, The Daily Beast reported that the National Security Agency is aware that the FSB -- the post-Soviet KGB -- is closely monitoring Wikileaks, though the U.S. has no "direct evidence" that the Russians are behind the days-long denial-of-service attacks that have brought down the Wikileaks website over and over again.

But why would the Russians care that much? In part, because Wikileaks founder Julian Assange has said that between the leaked cables and other information he got separately, high-level corrupt Russian officials should be worried. And some observers think that Assange's efforts to expose corruption in Russia could be more harmful to his site and himself than exposing America's secrets have been. One law enforcement source told The Daily Beast, "The Russians play by different rules," adding that they would be "ruthless" in their attempts to stop him.

(emphasis mine)

Russian leaders don't get worried, they get proactive, as in the subject of their concern ends up mailed to his family in a dozen parcel post packages, or they die mysteriously.