[UPDATE] Following the publication of this story, Microsoft confirmed with GameSpot that Xbox Live has not been hacked.
"Xbox Live has not been hacked," a company representative said. "Microsoft can confirm that there has been no breach to the security of our Xbox Live service."
The original story follows below
A hacker going by the name Reckz0r today claimed to have cracked Xbox Live, exposing confidential information for around 47 million users.
In a note posted on Pastebin, the hacker claimed to have "brutally owned" Xbox Live a few days ago, but decided to publish the data today.
A Microsoft representative has told GameSpot to expect comment from the company shortly.
The hacking claims come just two days after Microsoft announced its next-generation platform, the Xbox One.