Lies. That info actually applies to NiMH. The problem with leaving li-ion batteries plugged in for long periods is from heat, but the NITs don't generate much heat, so it's not really an issue.

I leave my 770s and my N800 plugged in most of the time when I'm at home, and haven't had any major impact on battery life.

The device has both overcharge and undercharge protection built in, and Nokia chargers are some of the best. Don't buy the aftermarket garbage.