It seems that either Viacom came to their senses about making Google turn over user data on YouTube, or they didn’t like the bad press that their suit was generating. They have reached a deal to protect the privacy YouTube watchers everywhere and will allow Google to anonymize YouTube user data.
Previously Viacom succeeded in getting Judge Louis Stanton of the U.S. District Court for the Southern District of New York to order Google to turn over as evidence a database what videos users watch, the users' computer addresses, and their usernames. Many groups including the Electronic Frontier Foundation argued that the order "threatens to expose deeply private information" and violated the Video Privacy Protection Act. Whether the Act, created when VCRs were high tech, could be applied to YouTube was debatable. Viacom and Google’s deal avoids the legal snarl all together.
If you are into deciphering legalese (and we can assume you are into self flagellation too) you can read the details here.