I laughed when I saw this.
Being I consider Apple's most powerful system to be a glorified toy, you can imagine my opinion of trying development on an iPad. (Although I am a former Apple stockholder [only a few shares])
The thing doesn't even have a real keyboard... That just can't be conducive to development.
It appears to use a 1GHz Apple A4 as the CPU and have AT MOST a data capacity of 64GB. (source) I wouldn't even want to think about trying to use modern-day Photoshop on a system like that. I imagine the touch screen precision also isn't very adept to graphic design.
As far as I'm concerned, the iPad is a bloated eBook reader. I'd be looking at the Amazon Kindle for that. For development, I'd be looking at a Win 7 workstation. If you really need a small and mobile machine for intermediate development I'd consider high-end netbooks or low-end laptops rather than what is essentially an eBook reader.