I just came online to see if an iPad version was in the works. I love my desktop version of TR, and use the iPhone version as a very useful capture tool; I don't really use the context based lists so much at the moment. I've just ordered an iPad for the flexibility and I'd love to see an iPad TR app, with as much functionality as possible. The only other option I'm considering is Omnifocus. They have the iPhone and the iPad versions, but I have a PC laptop, so I can't use the desktop version. I'd love to be fully synced across devices. The Omnifocus products also don't look as complete an implementation of the GTD methodology (for instance, its not clear where someday maybe and reference go, and I prefer the way TR captures thoughts, without having to do lots of thinking at the front end; save that for processing).
So to cut a long story short, I'm very keen to see TR on the iPad. Omnifocus is charging $40 or more for their iPad app and I'd pay that for a TR one!