I've been able to accomplish the "meander around, finding cool new places to work" thing pretty well with an 11" MB Air (and optional tethered iPhone).
It doesn't have the ridiculous battery life of an iPad, but other than that it essentially gives you the same portability without feeling like you're constraining yourself to a subpar development environment (I've tried doing serious web dev on an iPad, but the lack of a web inspector and the ability to remap caps lock as control are both dealbreakers for me).
It doesn't have the ridiculous battery life of an iPad, but other than that it essentially gives you the same portability without feeling like you're constraining yourself to a subpar development environment (I've tried doing serious web dev on an iPad, but the lack of a web inspector and the ability to remap caps lock as control are both dealbreakers for me).