You must add portrait support for most areas of the OS. I was sure that this was going to be my next "phone" (mobile computer) but what is the point of device which is pocketable which cannot be used on the go. I may as well put it in a bag. Think about it, the majority of the time you see someone with a touchscreen device they are using it in portrait. Examples: 1)Walking to work want to check my emails casually - single handed, so that I can carry my briefcase. 2) Check RSS feeds out and about.
3) Check the time single headedly.
4) Using Ovi Maps while walking in an unknown place (If I try to do this with 2 hands I will probably get hit by a bus - by adding portrait support you will actually be saving lives!