As was witnessed in their demonstrations at GDC, Sony is planning to have an Operating System running constantly in the background, just like one witnesses when using the Xbox 360 OS (aka Dashboard). They plan to have a "Blade" like pane that can appear out of the right hand side of the screen for viewing and participating in activities that the OS enables.
This include but are not limited to,
- Multi-User Voice Chat across all games, even outside of the games own UI
- Multi-User Video Chat across all games, even outside of the games own UI
- Notifications and messaging to be sent between users regardless of the games they are playing. More...
Credit: ars technica