Neither mourning the death of pal/maybe-lover Heath Ledger nor persistent tabloid play could stop The Wackness star Mary-Kate Olsen from having her fun—or finding arms to comfort her. According to eyewitnesses, Olsen bobbed to a DJ's beats and sucked face with artist Nate Lowman at Lower East Side watering hole Sweet Paradise in Manhattan late last night.

After parting with twin sister Ashley Olsen at a different club, MK turned up at the bar after midnight and parked at a side booth with hipster pals, according to witnesses. "It was weird to see her and her pals there with a bodyguard in the corner keeping an eye on her. She didn't look concerned with anything that had happened with Heath at all," one spy tells Radar.

As Olsen chatted with her crew, she'd casually slip in kisses with Lowman. "It was a deep passionate kiss, which she'd follow up with a lot of little kisses," says our witness. "She seemed to be very into him. She kept putting her hands behind his head and playing with his hair."

But despite cramped quarters inside the bar, not to mention the lurking bodyguard, MK went pretty much unnoticed. "Most of the people just walked right by her and didn't even pay her a second glance. She really fit in well here," says our snitch.

Calls and e-mails to Olsen's publicist were not returned by time of post.