Just want to add my perspective on what I would like to see on an iPad version of Pleco. My iPod Touch is great as a mobile platform for reference look-ups (aka, dictionary) and (hopefully soon) flashcards practice. However, the value to me in a larger scale platform that is the iPad (which is far less mobile) is a more interactive learning experience. Here are some suggestions in order of priority to me:
1) Handwriting practice with overlays and creative ways to "prompt" for the correct stroke order.
2) Interactive reading with characters, PinYin, and English translations (mdbg.net does a great version of this concept). Possibly following a textbook.
3) Contextual comprehension (spoken words, pick the visual...like Rosetta Stone). Make your own adventure, Chinese style!
Quite honestly, Pleco's implementation on the iPad will be the decisive factor in my decision to purchase either an iPad (walled garden), ebook reader (cheaper one trick pony like Kindle), or touchscreen computer (multi-functional but short battery like HP Slate). Each platform has their strengths and weaknesses but likely only one or maybe two (if you include desktop Pleco) will have full Pleco support.
So keep us in the loop so I can make an informed decision!