Media event set for September 9, launch likely ~10 days later.
New Pepsi-iTunes Promotion? [Update 3]
Pepsi has just ended a promotion in Canada featuring an iPod-an-hour giveaway. Apparently the new caps also include one entry into a new iPod-An-Hour giveaway, featuring iPod mini's.
A broken set of details are found in a MacRumors forum post, having been ripped off a bottle already in circulation.
Update: Apple has created a web page previewing the upcoming promotion. http://www.apple.com/itunes/pepsi/. 1 in 3 wins a free song on iTunes. Official Rules.
Update 2: Above pages removed. Here is a mirror of the page: Screenshot.
Update 3: Apple's official pages have been put back online.