Justin Bieber, 17, and Selena Gomez, 19, were on babysitting duty Saturday, taking care of Biebs' half-brother Jaxson. And the two look pretty comfortable with childcare!

Bieber turns 18 in a few days, but even at such a young age, he was up for the task of taking the little tyke out to lunch. It was Benihana for the trio ... wonder if little Jax got the steak and shrimp or the chicken and shrimp?

As Heidi Klum and Seal prepare their divorce and as Seal is off promoting his new album, Heidi's home with the kids, going it alone ...

The soon-to-be single mom took her brood to their weekend activities Saturday -- Henry and Johan to karate, and Leni to ballet. And what we noticed were the kids' superstar styles -- Henry's sporting an edgy Mohawk and Leni, 6 1/2, is carrying a cell phone!

The Project Runway boss was no less chic -- she wore a $3200 Rick Owens leather biker jacket to run errands. Hey, in LA, weekend casual is still haute couture!

Jessica Alba has certainly found her flow ... she and Cash look like the happiest couple around and they've got two adorable kids to boot!

Having started her own business, The Honest Company, and seemingly taken a break from acting, Jessica is able to devote lots of time to being a mom to Honor and baby Haven.

While Jess played with Haven on a blanket at the park Saturday, dad Cash hopped around the park with daughter Honor. And check out Honor's faux fur gilet! She's a fashionista in the making!

We can't wait until March 3! Lindsay Lohan will host Saturday Night Live that night; Jack White will be the musical guest.

It'll be Lilo's fourth time on the show -- her last guest appearance was in 2006.

Lindsay hasn't been booking many TV and film gigs since her legal troubles began (again) last year; just plenty of Terry Richardson photo shoots. So at least this will get her back on TV, outside of her cameos on Nancy Grace!

Okay, okay -- dude looks like a lady ... we couldn't resist!

But seriously, folks -- did Steven Tyler borrow his fiancee Erin Brady's flowery cargo pants or what?!

Who would wear makeup to go sweat at spin class anyway? Well, 90% of women in LA, that's who! But not Katie Holmes!

The practical actress wore sweats and a fresh face to SoulCycle Saturday morning to get her cycling groove on. Between this and her regular dance classes, this girl is one in-shape mom!

We never thought it would happen ... Italian hottie Elisabetta Canalis has brought her boy toy Steve-O back to the homeland to visit her parents!

Seriously?!

The MTV hostess with the mostess has certainly taken a step down after dating George Clooney. I mean how can a girl feel going from an Oscar nominee to a Jackass?

Jennifer Garner is still toting daughter Seraphina in her arms and she's still on carpool duty during these last days of her pregnancy.

The actress picked up her budding ballerina Violet Saturday at dance class but Jen had a full load with Sera in her arms and a bun in the oven! How much longer could she possibly have before she gives birth? For her sake, we hope it's not long!