First Week of September -- Will update this post

Sony: September 3rd

Android Geeks
Xperia Blog

Samsung: September 3rd @IFA

Phone Arena

"We’ve also heard persistent rumors about next-generation flexible displays, but we remain a bit doubtful. Luckily, it’s less than a month until Samsung kicks off its Unpacked 2014 conference, and that’s when we’ll find out."

Galaxy Alpha

Apple: September 9th

At WSJ

MacRumors
CNET

Sony