Kotaku's Brian Crecente recently received an official invitation for a Killzone 2 Preview at E3. The duration of this preview? Two and a half hours. Crecente assumes it has to be a hands-on demo.
Andrew Yoon, writer and editor of PS3Fanboy.com has also receieved an invitation for the pre-E3 event. The scheduled event runs from 9:30PM-12:00AM on Tuesday July 10th. This happens to run concurrently with Microsoft's planned press conference.
Additionally, Yoon mentions that only 150 invites have been extended to the press.