Which way now, Lindsay Lohan?

Up until this weekend's latest escapade, bad girl Lindsay Lohan was scheduled to spend the summer appearing in a bonanza of high fashion ads and marketing blowouts, culminating -- depending on your point of view -- in the horror flick "I Know Who Killed Me," featuring Lohan in the dual role of troubled stripper and high school teenager, or in her 21st birthday party extravaganza at Pure nightclub in Las Vegas on July 2 and 3. Just last week, she was bragging to associates about the 500 guests scheduled to fly in for Lindsaypalooza.

And then came the Saturday morning tiff between her Mercedes and the bushes, which led to Lohan's arrest on suspicion of drunken driving, with more charges possibly in the offing. Police have said that a substance believed to be cocaine was found. Since then it's been hard to keep up with the gusher of sordid news and images circling the Internet -- a series of photos showing Lohan appearing sacked out in a car around 4 a.m. Monday (an AA sobriety necklace hanging from the rear-view mirror). Lohan's representatives released a statement Tuesday that said she had checked into "an intensive medical rehabilitation facility on Memorial Day."

Has a tipping point been reached? Now that she's theoretically in line for a jail cell next to Paris Hilton's, will the rats begin to scurry from the ship? Or is this a temporary blip in her celebrity?

Several calls and e-mails Tuesday to Lohan's publicist, lawyer and mother went unanswered, and her manager declined to comment.

Undoubtedly, everyone who has signed on to the Lindsay juggernaut knew of her reputation -- her first stint in rehab, movie executives frustrated by her perceived lack of professionalism, the 24/7 partying dutifully chronicled by a platoon of paparazzi -- but still corporations were willing to gamble on her effervescent beauty.

Unlike fellow bad girls Hilton and Britney Spears, Lohan has high-fashion credibility. Two weeks ago, the most ubiquitous photograph from a Chanel fashion show in L.A. was Lohan looking radiant alongside the icon Karl Lagerfeld. Last week, black-and-white glamour photos of a topless Lohan in nothing but a miniskirt, lying amid rumpled sheets clutching a Jill Stuart patent leather satchel, made the rounds on fashion news sites and blogs. The photo was the first released from a print advertising campaign that the contemporary sportswear designer had planned to place in magazines starting in August.