The second bits of information came from Sony. At the PAL specific press briefing David Reeves said that they had about 12 announcements to make at Leipzig, far more than what made its way out at E3.
Some print media were given a private preview screening of Heavy Rain at E3. The developers (Quantic Dream) were also present at the Sony briefing and while they weren't able to talk about Heavy Rain at E3 outside of the private screening they did hint at more open access to information about the game at GC.
I really enjoyed E3 for the amount of games that were on show and the willingness of the developers to talk about their games. The GC's last show in Leipzig however promises to be action packed.
The Leipzig Games Convention is from August 21-24. It's looking more likely now that Heavy Rain is going to blowout there, and maybe, other exclusives shown behind closed doors will also appear there.
Sorry for the bad Link. Its actually