Now that the iPad is a few years old and people are using them more in day to day work, a common question asked in forums is that of being able to develop apps for the iPad on the iPad. The problem with this is that Apple has no plans that I know of to launch Xcode for the iPad. The reason for this is likely to be related to how tightly integrated the frameworks are with Mac OS X.
To develop for iOS devices while on the go typically requires that you have a MacBook running OS X along with Xcode installed. For some of us, we prefer to carry just an iPad around due to the impressive battery life, instant on and smaller form factor which all make it ideal to throw in a bag.