Details are sketchy at this stage, but it looks like a member of Goonswarm infiltrated BoB and was able to become a trusted and valued member of BoB's senior command. Today, they caused the disbanding of the BoB alliance and took 500 million ISK for themselves from the wallet.
Everyone's talking about this, but no one REALLY knows what occurred. More details will be provided here when I find out.
UPDATE: I've been too busy to follow this event and update this post accordingly, so instead I'll just link you to an excellent outline of it for you to read (if you haven't already!):
Massively: Further developments in EVE's 'Grand Theft Alliance' drama