To get the original "Droid" sound at startup you need to do the following:
Settings > Sound and display > Notification ringtone and select Droid.
The "Droid" sound will now play when you start the phone however any notifications will now also play that sound unless you set individual notification tones for each app/email account that creates notifications.
Still doesn't work. My droid doesn't sound on initial start up anymore but the keypad tones come back for the phone pad every other day without doing anything.
Sounds like a glitch to me.