Double-stick tape may have been the accessory du jour at the 84th annual Academy Awards last night as more than a few red carpet stars wore seriously plunging necklines.

Most uncomfortable, perhaps, was Rooney Mara in her deep-V white Givenchy. Pundits saluted her for breaking out of her "Dragon" girl black, but she kept checking to make sure all was in place. Viola Davis -- killer in emerald, body-hugging Vera Wang that ended in a plume of ruffles and pleats -- also showed some serious décolletage. And natch, Jennifer Lopez went really deep, too, in a barely there Zuhair Murad that may have needed a bit more tape during her onstage presentation. Yikes!

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But even if the gowns weren't plunging, most of the ladies were giving Oscar the cold shoulder. From gamine Michelle Williams' coral stunner -- a chiffon ruffled, strapless Louis Vuitton with a peplum -- to the swath of metallic satin by Marchesa that encased Stacey Keibler, shoulders were predominantly bare.

Natalie Portman wore a strapless, polka dot, red vintage haute couture Christian Dior number from 1954 -- very Grace Kelly. Jessica Chastain was positively regal in Alexander McQueen's black-and-gold embroidered confection. Gwyneth Paltrow topped her one-shoulder Tom Ford jersey slither with -- a cape. Likewise, Glenn Close, bombshell in strapless hunter green Zac Posen tossed a jaunty matching tuxedo jacket over her shoulders.

Finally, red carpet queen Angelina Jolie wore Versace's strapless asymmetrical gown with a daring, thigh-high slit.

Some opted for more cover, including best supporting actress winner Octavia Spencer, perfect in a shirred, white, sparkling Tadashi Shoji with capped sleeves. But covered didn't always work: In a rare miss, 20-year-old Shailene Woodley looked too grown up in Valentino couture.

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As for the guys, it was tuxes as usual, save for Sacha Baron Cohen, who wore a "dictator's" uniform by, he said, John Galliano. Poor Ryan Seacrest wore pancake mix on his Burberry tux after the comedian pranked him. Seacrest, always prepared, had another jacket on hand.