The N900 runs the slick new Linux-based Maemo 5 OS, but Nokia is already dishing up details on Maemo 6. Expected in late 2010, it'll introduce a portrait-mode, support multitouch and capacitive touchscreens, and have a desktop filled with widgets.
The N900's Maemo 5 OS, shown below, doesn't currently support portrait rotation:
The new info comes from the Maemo Summit, where the Fins also demonstrated an official Qt port specifically designed for Maemo 5. The Qt port (available now as a preview release) lets developers use a common framework to build apps for the N900, future Maemo 6 devices, in addition to Symbian and Windows Mobile.