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Aston Grimaldi II, chief investment officer of Dune Capital Holdings and believed to be related to the royal family of Monaco, boldly issued a letter offering $150,000 to anyone who can produce the video of Sen. Barack Obama at a 2003 banquet praising Palestinian scholar Rashid Khalidi (this event became a ready excuse for Jew-bashing). Dirty Harry's Place, a conservative blog, mentioned that anonymous donors offered an additional $50,000 for the same tape for a total of $200,000. The L.A. Times is in possession of this video, but refuses to release it.
Rush Limbaugh is on top of this hot topic, and has links to a variety of sources.
UPDATE: Little Green Footballs has reader comments that raise doubts as to the authenticity of the Grimaldi letter; nevertheless, stonewalling on the part of the L.A. Times sounds quite suspicious, and McCain should offer a much larger reward for anyone who can produce that video.