Here's a short list
1. Power-based settings (i.e. brightness changes when plugged in and on battery). A very BASIC feature.
2. Hiding folders in the music player. Blackberry gives the options to NOT include certain folders when searching for music. When I listen to music, I don't want to hear 50 ringtones.
3. User Customizable Profiles. Silent, Vibrate, Work, Home...Why not?
4. Alarm based auto-power on. If i set an alarm, and my phone is powered, but not on, it should be able to power on and wake me up. This is a GREAT feature for people that rely on alarms.(like myself)
5. Bluetooth profiles. I'm not new to mobile devices, so I know this is something they're currently working on. But come on...all we have is the headset profile. What come of lame-o **** is that? a2dp and wireless file access would be great, as well as phonebook access and callid and sms info for car kits...
There's more that I'm forgetting, but that's the gist of it. I realize that we're all technically beta testers at this point, but they should have released a more polished product to the masses. It would have helped their word-of-mouth sales greatly. Look at all the vista negativity. I've been using it without any problems since it was RTM, but people hate it because 'they heard' it has tons of problems. The average joe isn't going to want the g1 because 'they heard' it can't do this, or it can't do that. I personally love the device, and it has great potential, but t-mo and google may have shot themselves in the foot on that front.