 In the context of the article, who is Si and what does he do?
Let Si Get This During a typical lunch time at the Royalton Hotel restaurant in midtown Manhattan, The New Yorker 's Tina Brown might be installed at her usual table, and Vogue 's Anna Wintour might be at her usual table (chewing on her usual meal--a $25 hamburger). Vanity Fair 's Graydon Carter might be there too, although he has transferred his main allegiance to a place called Patroon. Filling out the room are other editors, publicists, and writers from these magazines and GQ and House & Garden and so on. And one man, who probably isn't there himself, picks up every tab. Some of the lesser fry may even utter the Condé Nast mantra--though it is hardly necessary at the Royalton--as they grab for the check: "Let Si get this." S.I. "Si" Newhouse Jr. and his younger brother, Donald, control Advance Publications, one of America's largest privately held companies. (Estimate of their combined wealth: $13 billion.) Donald tends to Advance's hugely profitable newspaper, radio, and TV holdings. Si runs the less profitable but more glamorous properties. These are the 15 Condé Nast magazines, including (in descending order of fabulousness) Vogue , Vanity Fair , GQ , Condé Nast Traveler , House & Garden , Allure , Details , Self , Mademoiselle , and Glamour ; ; and Random House. The expense-account lunch is a hallowed journalistic tradition. But consider a day in the life of an editor working for Si Newhouse. It's a closed economy where almost all human needs and desires can be gratified with a miraculous, unlimited currency called the Si. A Lincoln Town Car is waiting outside your door in the morning to take you to work. The car, which costs $50 an hour, is written into your contract. First stop, breakfast with a writer at the Four Seasons. When you reach the office, you realize you're out of cigarettes. No problem--you send your assistant to buy a pack for you. She gets reimbursed from petty cash ($3). (Could be worse for the assistant: She could be forced to pick up her boss's birth-control pills, or her boss's pet from the vet, or presents for her boss's children--regular duties for Condé Nast underlings.) You've forgotten to return the video your kids watched yesterday, so you have a messenger take it back to Blockbuster. Si spends $20; you save a $1.50 late fee.
 Si, or The Si, is the person responsible for covering the absurd expenditure of the Condé Nast magazines.
 Si, or The Si, is the person responsible for covering the absurd costs of of the New York Editor lifestyle.  Si, or The Si, is the person responsible for covering the absurd expenditure of New York parties.  Si, or The Si, is the person responsible for the culture that has developed around the writer/editor lifestyle.  Si, or The Si, is the person responsible for covering the absurd expenditure of the Condé Nast magazines.