Pixi (if it is, someone forgot to give the Premier department the memo), though the note's mention of Simply Everything and Right Plan Promise suggest that the news is going to be plan-focused, not hardware-focused. There's a curious "anymobile" subdomain dug up by a Boy Genius Report tipster that could have something to do with it -- right now it just leads to a "Coming Soon" page -- but otherwise, your guess is as good as ours. Free unlimited data for everyone, perhaps? Ooh, a sudden reversal of strategy with a move to LTE?
[Via Boy Genius Report, thanks Matt G.]