If you have an ipad, chances are great that you already have an iphone, so at the same time you sure have the tumblerette app for iphone, which is now called simply Tumblr for Iphone.  Turns out that this same app can be used for the ipad and you download it from the itunes store.

Still there are complaints that not more than 1 photo can be uploaded in photo posts.  And video uploads do not work, seems to be related to Vimeo.