Here are some shots of Nicole Richie and new-beau Joel Madden this weekend, doing what all young celebs should do when they go out: using a fucking driver. Meanwhile, Nicole couldn't keep up the habit and herself away from the wheel–according to TMZ, the starlet's weekend ended with flashing lights and counting backwards from 100 by seven:

TMZ has learned that Nicole Richie was arrested for DUI early Monday morning. She was booked at 4:50 AM today and was released 45 minutes ago. The booking sheet reveals Richie is 5'1" and 85 lbs.

So…that's not a lot of lbs. Gotta believe that if "one drink" could put Paris Hilton over the legal limit, that same drink would have Nicole in the drunk tank for the night.
More details to come.

UPDATE: Like Whoa. TMZ's newest update shows that not only were my jokes way off, but the situation was far more potentially dangerous that I originally assumed:

We're told her SUV was spotted by two motorists going the wrong way on the 134 freeway in Burbank. The drivers called 911.

When the CHP responded, Richie was stopped in the carpool lane and was alone in the vehicle. When cops approached the vehicle, Richie was on her cellphone.

Law enforcement officers tell TMZ Nicole Richie admitted she had taken Vicodin and smoked pot.

A preliminary alcohol screening device revealed that Nicole was not under the influence of alcohol.

Wrong way on the freeway? Yikes. Driver. Get one. Use him/her always.

Update #2: Mugshot Richie.

[Source, Source]