That's the big question right now, it was said she'd be on the red carpet but yet no one saw her or got a small glimpse of her. Neither was she spotted in the hall... BUT she attended the Vanity Fair Oscar party later on :) Rundstedt found one picture of her at the party and maybe more will surface soon.
By the way, the show itself was kinda boring with one-half surprise at the end (Crash winning best picture) but apart from that and Clooney's speech, nothing outstanding happened. Stewart was a solid host and had some great lines but something was definitely missing this year.