If the iPod nano is paused, and you
press the Sleep/Wake button to turn
off the screen, the following behavior
will take place:
For 36 hours after pressing the Sleep/Wake button and turning off the
screen, iPod nano is in Standby, and
will quickly wake up when you press
the Sleep/Wake button again.
After 36 hours in Standby with no activity, iPod nano will shut down
automatically. Pressing the Sleep/Wake
button after iPod nano is shut down
will turn on iPod nano, and boot to
the main Home screen.
(Your iPod nano is considered paused if there is no music or FM radio playback, or an active pedometer session.)
Additional Information
A fully charged iPod nano provides up to 24 hours of music playback time.
Update: With the new update from Apple (v1.2), it is now possible to remove icons that you don't use, and to change the size of the icons. Under Settings->General->Home Screen you can show/hide individual icons.
I don't believe that you can delete the icons. You can rearrange them. I moved the ones I'm not interested in to the last screens so they are mostly out of the way.
Best Answer
According to Apple Support:
Additional Information