Android: If you find yourself preferring a different keyboard in portrait mode than in landscape, free app Keyboard Manager will automatically switch between them on a rooted Android phone.
Keyboard Manager is root-only at the moment, and the install process isn't quite as straightforward as a regular package, but it's pretty handy (and not too difficult). You'll need an app like Root Explorer to pull it off, but as long as you do, it's just a matter of moving the .apk file to /system/app and changing the permissions. Once you reboot, it should show right up in your app drawer.
The app itself is pretty self-explanatory: just pick which keyboard you want in each screen orientation, and it will switch them for you automatically. It's still in development, and is not without its quirks — unfortuantely, you have to orient the phone before you bring up the keyboard (it won't switch from one to the other instantly) — but it's still a godsend for those that prefer, say, previously mentioned Swype in portrait mode but want a more conventional keyboard in landscape mode. Hit the link for installation instructions and to download the app (you'll need an account at the XDA-Developers forums to do so).
Keyboard Manager is a free download for Android devices.
Keyboard Manager - Dual Keyboard: Portrait/Landscape Switch [XDA-Developers via Talk Android]