Owner of a GTA01v4, using Qtopia on Neo1973.
With the latest 3.4.1 snapshot, I am able to make and receive calls, send and receive SMS and I use contacts for that.
The next area in which the Qtopia flash image needs improvement is better battery time now. It suspends, and with console=ttySAC0,115200 removed from bootargs_base, it even wakes up with the GSM part working, but it does not wake up on incoming calls or SMS, so you are not getting notified if you turn on suspend. If you press the AUX button, the Neo will wake up and inform you of missed calls and should also inform you of received SMS.
At the moment (with suspend not enabled, which is the default) Qtopia lasts about 3-5 hours, depending on the amount of use now.
Be sure to disable Bluetooth to get that kind of standby time!
I seem to get a maximum amount of around 7 hours of raw standby time, if there is no use and the phone is not getting any touches and just laying on the desk with Bluetooth disabled and the display is always off.