Here are the official details for the 3.50 update:

The PS3 system software update (v3.50) is adding support for Blu-ray 3D Disc Playback, and it will be released shortly.

Additional new features in the 3.50 update include:

• Facebook Integration: Developers will be able to create PS3 games that have more interaction with Facebook. Once compatible PS3 titles are available, PS3 users can choose to access public information on Facebook – including user name, profile, uploaded photos and friends list – to enhance their gameplay experience.
• Grief Reporting Function: Users can send claim reports directly from the XMB for any inappropriate messages they receive from other PlayStation Network users. This feature is accessible from the option menu of the messages list in the FRIENDS category.

For more details and instructions on how to update the system software for the PS3 system, please visit http://www.us.playstation.com/PS3/Features/SystemUpdate.