Single handed typing on smartphones can often be a slow and frustrating process (unless you have something like Swype). It seems, though, that Microsoft may have a solution for this problem in the form of the new Arc Soft keyboard for Windows Phone 8 devices.
As you can see above the keyboard is curved so that all the keys are well within your thumb’s reach. In addition to that, the keyboard reduces the number of keys by assigning multiple characters to a single key. How exactly this is supposed to work is yet unknown but Microsoft is probably using some form of predictive text input such as T9.
Also, if you notice, the phone in the picture is an HTC Trophy, which is an existing Windows Phone 7.5 device. That means existing devices could also get this keyboard through the Windows Phone 7.8 update.
Although the keyboard does seem to be taking up a lot of space, it looks like it would definitely make one handed typing a lot easier.