Wow, not for me. I've worked with both a convertible and a slate Tablet PC and I vastly prefer the convertible, precisely because I found programming with pen impossible. One of the two thousand projects I have on the stack of "things to do in my copious spare time" is a customizable pen keyboard / input editor, precisely so I could dedicate virtual keys to, say, { and } characters. With such a thing, I could imagine programming with pen.