One important issue with tablet computers that is getting little attention is the screen aspect ratio. Some time ago I wrote about "aspect ratio hell" while trying to decide how to crop holiday photographs. The answer seems to be that you have to crop each photograph independently for each way the photograph is going to be output or displayed. For photographs, the variety of different aspect ratios is a perplexing problem that has no good answer.
Tablet computers have the same problem except that the responsibility lies with app developers who need to make their app work well with the aspect ratios of their target platforms. Aspect ratios for a tablet needs to take into consideration that it will be used in both portrait and landscape mode. The iPad has an aspect ratio of 4:3 (AR 1.33...), which is the same as the iPod Classic while the iPhone and iPod touch have an aspect ratio of 3:2 (AR 1.5). Anyone trying to develop apps for Apple products needs to take this difference into account. On the other hand, both Blackberry and Samsung has announced their Android based tablets with a 7 inch screen which has an aspect ratio of 128:75 (AR 1.706...), which is close to 16:9 (AR 1.77...).
When we look to media, television uses 16:9 and most cinema has a higher ratio like 2.40:1 except for iMax (AR 1.44) which is much squarer. Books and newspaper use a 3:2 ratio (AR 1.5) while magazines tend to be broader with a lower aspect ratio. Frankly, anything with an aspect ratio of more than 3:2 tends to look unnaturally skinny when viewed in portrait mode. A cell phone can get away with a higher aspect ratio because it has to be pocketable, but larger devices meant for viewing both media in both landscape and portrait mode needs to keep its aspect ratio to 3:2 or less. For example, the Kindle, which is mostly used in portrait mode has an aspect ratio of 4:3 (AR 1.33...). From this point of view, the Samsung and Blackberry tablets seem to be designed to be used in landscape mode and not in portrait mode. I hope that other tablet makers do not make the same mistake.