>>240 I think the ceremony itself is restricted to nominees, guests of nominees, cast, crew of nominated pictures and their guests. Then presenters are thrown in there (presumably with their guests). That's a guess, I genuinely have no idea.
However, the after parties are 'anyone who has a pulse' events. Some of those snapped at the Vanity Fair and Elton John parties were Z-list: Monica Lewinsky, anyone? Yeah.
So, I imagine that EO might have had an invite, went, but didn't get snapped at a party. I don't think she has the firepower to wrangle a presenter gig (whispers: I really don't think TH does either).