Saw this over on NeoGaf

 @geoffkeighley: Just spoke to Phil Spencer (@XboxP3), he promises tomorrow is all games at Xbox. 20 titles on stage. More in the Spike preshow.

nothing special about this. we know 15 are exclusive, the other 5 are multiplatform...

E3 is going to be epic.

Great... I hope some games surprise me (I mean not announced yet).

And Kaz...

no way are they going to announce the 15 exclusives at E3. they will keep some few games for other events

wow! that is a staggering amount to unviel on stage, really makes me wonder how much time they'll spend on each one..I guess if it's 5 minutes that would be an hour and 40 min

20 games!! So excited to see what they have in store!

How much GAMEPLAY will be shown?

Here's what doesn't count: prerendered, in-engine cutscenes, concept art, live action, developer interviews

If gameplay of more than 5 games are shown I'll be shocked

Actually 22

The pre and post show will have a new game announcement on it from MS that is exclusive.

LOL