When the iPhone was first released, there was a lot of hype and media coverage about its landscape mode support and cool auto-screen-rotation feature. What most journalists forgot to mention is that landscape orientation was only supported in 3 applications (Safari, iPod and Photos). The menu and all the other applications were stuck in portrait mode just as in every other phone.

It took 2 years and tons of complaints from iPhone users before Apple finally implemented landscape support in a few more apps (the email client most notably). This by no mean means full landscape support across the board. The menu and several apps (Calendar, Google Maps, Weather, etc) are still stuck in portrait mode. The YouYube app is still stuck in landscape mode (which is a real pain when you just want to watch videos while browsing the web. You end up having to rotate to watch the video then rotate back to continue browsing). Some apps support both orientations but restrict some functionalities to a specific orientation (the CoverFlow view in iPod for example is only available in landscape mode while its list view and main menu are only available in portrait mode). The grass isn't that much greener on the other side of the fence.

When it comes to third party applications, the situation is the same as on Maemo: developers can choose which orientation they support. In practice, pretty much all iPhone apps support portrait mode. Landscape mode on the other side is a lot less common. Typically, landscape mode is supported in apps where it really makes sense (apps that display photos or videos for example).

The issue of screen orientation on the N900 is slightly different though. Regardless of whether you call the N900 a smartphone, a mobile computer or a cyber toaster, the fact is that many N900 use cases are identical to those of a mobile phone. You use your N900 standing up in the bus and in the subway with one hand grabbing the rail. You use your N900 in the street with one hand grabbing the bag or the kid. You use your N900 in the supermarket with one hand pushing the trolley. In all those common situations, one-handed portrait use is mandatory. And in general, when you just want to check something out quickly, it's much easier to grab your phone with one hand and do everything one handed in portrait mode.

Having a portrait mode phone with spotty landscape mode support is much easier to sell to mainstream users than the oposite. Nokia could try to implement portrait mode support only in applications where it makes the most sense but they would have to challenge the view that most people have that the default use case of a phone is in portrait orientation. Implementing portrait mode support across the board might be a more realistic goal (if they want to go mainstream anyway).