The hottest party of the Christmas season is going to be thrown by Roman Abramovich. The Russian billionaire just bought a waterfront estate on St. Barts for $90 million, the most ever paid for a home in the Caribbean. Since Microsoft co-founder Paul Allen is not throwing his annual soiree this year, Abramovich’s will be the “It” party of the social season. The only debate is whether it’s going to be held at his new, 70-acre estate on Governor’s Beach or at a local restaurant. The dilemma? Finding a catering team on the tiny island large enough to feed 250 picky guests.