I believe I have found my ideal writing tool. For the last couple of months, I have been drafting text using iA Writer on the iPad. While the softward keyboard is cumbersome to use, I find the focus the combination gives very inspiring. Nothing but me and the text, no IMs or emails to disturb me. I have turned off notifications on the iPad, so not even a ongoing game of Words With Friends can spoil my productivity.
Today I was out shopping on Oxford street, and on a whim I picked up the iPad keyboard dock. This thing is awesome! It has the required special keys to interact with the iPad's functionality, but otherwise it feels just like Apple's other excellent keyboards. It holds the iPad vertically in just the right angle, and plugs into a power source, as well as external speakers if I need music while I work. In short, I am in love.
I expect this to be my primary writing tool for the near future. If I'm going to nitpick, the only thing I am hoping for is higher DPI on the next generation of iPads so that iA Writer can fit a bit more text per line. One final trick; The keyboard lets you switch between languages with cmd-space. Exactly the same combination I use to switch between norwegian and english keyboard layouts on the mac. Pretty awesome.