At the end of October Wayne Bivens-Tatum posted a nice concise 18-step process for downloading a book from Ebrary and loading it on a portable reading device. I just wanted to add that I sat in on a product demo earlier this month and can confirm that at this time it is NOT possible to browse Ebrary from your iPad and download a book directly to it. You CAN download a chapter or PDF page range, which is nice, but as suggested by Wayne and the commenters in his post, the current process isn't likely to win many converts to this welcome feature. Ebrary suggested they're working towards creating separate apps for each of the smartphone platforms (hopefully including iPad). I have no idea about the Kindle though.
As noted in the comments, Wayne has also ported his blog post to a LibGuide, and has given permission to copy it and modify as necessary for your institution.
Thanks for the excellent information Wayne!