Contrary to what you may have read here and elsewhere, it seems that Polonium 210 is not exactly hard to get, at least according to William J Broad in this article in today's New York Times. This complicates the story, to say the least:
The complicating factor is the relative ubiquity of polonium 210, the highly radioactive substance found in Mr. Litvinenko’s body and now in high levels in the body of an Italian associate, who has been hospitalized in London. Experts initially called it quite rare, with some claiming that only the Kremlin had the wherewithal to administer a lethal dose. But public and private inquiries have shown that it proliferated quite widely during the nuclear era, of late as an industrial commodity.
“You can get it all over the place,” said William Happer, a physicist at Princeton who has advised the United States government on nuclear forensics. “And it’s a terrible way to go.”
Today, polonium 210 can show up in everything from atom bombs, to antistatic brushes to cigarette smoke, though in the last case only minute quantities are involved. Iran made relatively large amounts of polonium 210 in what some experts call a secret effort to develop nuclear arms, and North Korea probably used it to trigger its recent nuclear blast.
That last sentence ought to make us a bit nervous. It seems that the "axis of evil" already has plent of nuclear weapons, not even counting nuclear bombs.
Some industrial anti-static devices reputedly contain as much as ten lethal doses. It maight take some chemical sophistication to remove it.