Dana Milbank/WaPO lied about Secret Service; may have lied about "kill him"
In cooperation with the Palin campaign, [the Secret Service has] started preventing reporters from leaving the press section to interview people in the crowd.
As could be expected, various "liberal" sites rushed to retransmit Milbank's claim; for instance it got almost 1000 comments at the HuffPost (huffingtonpost.com/2008/10/16/secret-service-blocking-r_n_135336.html).
However, the Secret Service denies that there's such cooperation (link), pointing out that members of the press are isolated as a matter of course.
And, Milbank was one of the originators of the "McCain's angry mob" meme, when on the 6th he claimed that an audience member at a Clearwater, Florida rally had shouted "kill him" (second link above). Although Milbank later pointed out that the remark had been made in relation to William Ayers - and as shown by a correct reading of his post - many others played dumb and assumed that the remark had been made about Barack Obama. If Milbank hadn't wanted to give the wrong impression or help start a meme he would have written the article in a different fashion.
Now, it turns out that the remark might have been made, or it might have been "tell him" instead (link). That's less clear-cut than the lie about the Secret Service, but based on the article's overall attempt to smear Sarah Palin and her supporters, it's certainly not impossible that Milbank simply made it up. Note also that there were two alleged instances of "kill him"; the second occurred in Scranton PA and didn't involve Milbank; the Secret Service has been unable to find any evidence that anything like that was shouted in Scranton (link).