That's unlikely (read: practically impossible). iPhone SDK and Xcode developer tools are designed to run on Mac OS X on Intel x86 processors. iPad's processor is a 1GHz ARM processor. It's a different architecture and is inadequate for running those tools effectively anyway. (This can change if Apple can and be willing to develop a version of said developer tools natively for iPhone OS with sufficient performance).
You can use a text editor on an iPad to write code but you are not likely to be able to compile, test, and debug it.
By the way, in case the device can be jailbroken, you'd be able to run native gcc for iPhone OS to compile your app (as you can currently do with an iPhone/iPod touch too). You won't be able to use Apple's proprietary tools like Interface Builder but you'd be able to compile Objective-C sources and test and debug your app.