IMHO the only function I see logical to be in a portrait orientation is the phone function. A button to click on and flip the web-browser to portrait mode could be a nice addition, but other than that - I don't think there is a generic need for portrait mode.
If someone who makes an application and wants it to be able to switch between landscape and portrait modes - so be it. But Nokia shouldn't have anything to do with it... Just IMHO.