First screenshot: This was running on the Xbox 360.
poster leaked by Kotaku.
Game map from Black Flag
New "Skull and Crossbones" Assassins brotherhood logo
New Character, Edward Kenway (supposedly Connors grandfather).
Fellow redditor KingCharlesMarlow overheard info from Ubisoft employees talking about black flag.
Trailer will have Johnny Cash.
"Survival is the Only Thing Worth Dying For." is the tagline
Heavy focus on naval battles.
Fan Made Trailer
"The Examiner also suggests Black Flag is presently running current-generation technology, though Ubisoft has plans to release the game on future platforms."

Source:
http://www.reddit.com/r/assassinscreed/comments/19bvdi/discussion_assassins_creed_4_black_flag_conference/

Assassins Creed 4: Black Flag Conference First ScreenShots! + Info
Assassins Creed 4: Black Flag Conference First ScreenShots! + Info
Assassins Creed 4: Black Flag Conference First ScreenShots! + Info
Assassins Creed 4: Black Flag Conference First ScreenShots! + Info
Assassins Creed 4: Black Flag Conference First ScreenShots! + Info