Ok I just discovered a way to do so. Kindle for iPad/iPhone doesn't allow an official way of loading your personal documents to be loaded onto your app. So a nifty trick is to use the iPhoneExplorer app on your Mac and open your iPad/iPhone in it. Then just drop the .mobi book onto Apps>Kindle>Library>eBooks. That's it.
Hmm, I'm fairly sure I loaded books on the Kindle app for the iPad by just mounting it, the app shows up as a folder. Or maybe that was iBooks...
I just did it by browsing on my iPad to the github source for the sicp.mobie and clicking "view raw". The iPad then offered to let me open the file in the Kindle app.
It doesn't see to sync to my Mac Kindle app though.
That works too. Cool.
The Kindle app shows up in iTunes when you sync your iPad, same place as the iWork apps. You can just drag & drop the .mobi file there and it will load it into the Kindle app on the iPad.