This was just one example, but of course the biggest crave to portrait comes from fact that right now it's quite hard to use n900 comfortably while on go (walking, on que) to just check things fast and have another hand free.

And purpose my mockups was not only to show advantages of portrait mode but the habit of UI designers to over-estimate the space needed for buttons and elements. One of biggest reasons I haave not used KDE/Gnome on my pc with (1024x768 resolution) has been for years lack of pixel wise themes. I mean even 20 pixels mean A lot to me. For example windows xp without candy and default fonts is quite opitmized (browser, explorer). I just hate with passion all the padding and extra space in all themes across the differen OS's. To me too many look like they are for old people or for tv resolutions. Same thing applies to N900. More compact. Pixel wise usage importance goes up exponentially when resolution goes down.