It appears that reports of a systemic hack of Bungie.net to obtain a slew of Xbox Live accounts may be blown out of proportion.
Microsoft sent their official response to this morning's story to me just a bit ago:
Recently, there have been reports of fraudulent activity and account theft taking place on the Xbox LIVE network. Security is a top priority for Xbox LIVE, and we are actively investigating all reports of fraudulent behavior and theft. Any customer with a question about the security of their Xbox LIVE account should contact 1-800-4-MY-Xbox, and
an Xbox Customer Service Representative will help them understand our security policies and procedures.
A Microsoft rep went on to tell me that while they are investigating the concerns, they have not found any security breach of Bungie.net or Xbox Live accounts. Brian