Hey, this has been covered a little in the press, but I just found that the investigator never got credit, so here we go:
On April 15, Anupanama Narayanswamy writing at the Real Time blog, a project of the Sunlight Foundation, reported that Thomas Loeffler, a co-chairman of the McCain campaign, was an active foreign lobbyist for the Royal Embassy of Saudi Arabia. She noted that Loeffler had apparently suspended lobbying activities for the Saudis while serving with the McCain campaign, but the Saudis continued to pay his firm some $3.5 million dollars while it was doing no lobbying for them. What were the Saudis paying for? Loeffler's firm and the Saudis wouldn't say. About a month later, an item in Newsweek recounted the same information Narayanswamy found. The story was picked up by other outlets, and Loeffler resigned from the campaign soon after. Good to see that some reporters are doing some digging into the campaigns.
Disclosure: I'm on the board of Sunlight.