I haven't done extensive testing but it seems that A-GPS will work in several European countries without data roaming active. Worked in Spain in July on the iPad 3 (you can have data disabled but the device is connected to the 3G network) and also on a Nokia phone some time ago in Italy when the carrier's foreign data billing was broken and I hit the 50€ limit in just a few hours -- the actual charge was less than an euro. The phone was complaining that there's no data connection but A-GPS got a quick fix.