According to version 2 of the User Interface Design and Interaction Guide for Windows Phone 7 now available from Microsoft, the Windows Phone 7 OS Chrome has two primary components: the Status Bar and the Application Bar.
The brochure defines the Status Bar as "an indicator bar that displays system-level status information in a simple and clean presentation in a reserved space in the application workspace. It automatically updates to provide different notifications and keeps users aware of system-level status". It is what we called the Taskbar in Windows Mobile/Phone 6.x and below.
There are ten icons capable of being displayed in the Status bar and those are:
1. Signal strenght
2. Data connection
3. Call forwarding
5. Wireless network signal strenght
6. Bluetooth status
7. Ringer mode
8. Input status
9. Battery power level
10. System clock
Of all the above, the System clock is the only one which is displayed at all times and double tapping the Status bar brings up other relevant information (if any) which is active on the screen for about eight seconds, after which it automatically hides.