If I where you I would not get an N900, this as the hardware and the software are on the way out. The N950 was just released btw and that one is also on the way out, as Nokia is only going to sell Windows based phones in the foreseeable future. An Android phone will thus make you much happier. You probably mean 6in4/proto-41 with "6to4", but that protocol does not work behind NATs and quite often 3G networks are NATted and thus that won't work. I also wonder how useful it is to have a public IP on a phone, as it is the device in your pocket, thus you won't need to SSH into it or so from a remote location....

have you bought that phone? if yes did you cope with aiccu on maemo?