From a technical perspective, yes it absolutely can run on the iPad (anything running iOS 4 actually).
However to be able to install it, it would need to be featured in the app store. I wouldn't completely rule it out in the future, but at the present moment I've really no plans to jump through that bureaucratic mess.
If there turns out to be a huge demand for it on the iPad going forward then I of course will certainly consider that. At this point in time however the vast majority of people using ZenEdit are on Windows, with a few folks on Mac.