Adding to the Amp orange/grape rumors, on December 19, 2007, Pepsi filed to protect the trademark of
Amp Energy Elevate, with the associated logo in black/white:
Not sure if that factors into this discussion, but take it for what it is.
And as far as the Slice rumors, just a few days before the above filing, on December 4, Pepsi made two other filings:
Sierra Mist Undercover Orange and
Sierra Mist Free Undercover Orange. One must assume these are for orange-flavored drinks, based on the color logos:
Thanks to Trademork for the tips. 