Clint Eastwood squinted like Dirty Harry Tuesday night as he took aim at Michael Moore. "Michael Moore and I actually have a lot in common - we both appreciate living in a country where there's free expression," Eastwood told the star-dotted crowd attending the National Board of Review awards dinner at Tavern on the Green, where Eastwood picked up a Special Filmmaking Achievement prize for "Million Dollar Baby." Then, the Republican-leaning actor/director advised the lefty filmmaker: "But, Michael, if you ever show up at my front door with a camera - I'll kill you."The audience erupted in laughter, and Eastwood grinned dangerously. "I mean it," he added, provoking more guffaws. Sitting well out of range at a table in back, Moore - who received a special "Freedom of Expression" award for his anti-Bush polemic "Fahrenheit 9/11" - chuckled. What a difference from last summer, when Moore's supporters complained that death threats were arriving almost daily and the director showed up at the Democratic Convention with a security detail. Back then, Moore was outraged when CNN anchor Bill Hemmer suggested during an interview that some folks might want to see him dead. "Can you think of any other interview in the history of television where a politician or a movie director was asked about people wanting to see him dead?" Moore seethed to me at the time. But, in this case, Moore's rep told me yesterday: "Michael laughed along with everyone else, and took Mr. Eastwood's comments in the lighthearted spirit in which they were given." Phew.