Well, I didn't see that one coming. Amazon have posted a page dedicated to the Kindle App coming to various tablet based computers and in the first graphic it specifically mentions the Apple iPad. Read further down the page and it reads "Read Kindle Books on Your Tablet Computer Including the iPad".
This is great news as it will open up a whole world of great eBooks from Amazon. I personally think this news comes in combination with those rumours that Apple have been struggling to seal some deals with various publishers. Maybe this is their saving grace, that the iPad Kindle App means they have a tonne of content for the April 3rd launch. Whether this is the case or not, the Kindle App will certainly find its way onto my iPad for certain.