this is crucial. the batt will drain while it's just sitting on your desk if you don't have the hold on. there's nothing more frustrating that picking up your ipod after not using it for a few days, and having no charge.
On my 2nd gen 10 giger I still get about 7 hours out of the battery. They keep their life pretty good. Just remember the few tips I've learned to prolong life:
-turn off and keep off backlighting
-do not use the EQ feature on the iPod
-do not shuffle between lots of tracks while listening (it causes the harddrive to wake up to refill the buffer)
-avoid operating the unit in extreme temperatures (heat/cold) as it will slightly affect operating times
They had a great article on the iPod in the August issue of MacWorld (think that was it). They used the above list as the method behind Apple saying that an iPod could run for the advertised 10 hours.