It's the merest hint of a whiff of a rumour, to the extent that even the source, Cinema Blend, are at pains to say they're not sure they believe it. But the story goes that Rachel Weisz, former squeeze of reported director Sam Mendes and recent co-star of Daniel Craig (in Dream House) is being seriously considered for a plum role in Bond 23. Not as a bond-girl, but as the villain.
Blend say their man on the inside has been proved right in the past (he called Black Widow being in Iron Man 2, for example), even while emphasising that "things can change in a heartbeat" and the process at the moment is merely brainstorming (not to mention that MGM's internal ructions will likely significantly delay proceedings).
But we know that Peter Morgan has been working on the script for a while now, so even if Weisz proves to be a false lead, it's just possible that this could be our first hint of an uber-villainess heading up the shady organisation that Bond has been tracking since Casino Royale.
We've had a female Bond villain before though: Sophie Marceau's Elektra King in The World is Not Enough. Scarily, that's eleven years ago now, but in Bond terms it's still recent memory. So take this with a cellar full of salt for now, and remain coolly unconvinced. But by all means speculate wildly below. If Quantum has a female figurehead (an M in negative?) who would be the best possible casting?