Autographed ebooks are a relatively low-cost, high value item that many readers will appreciate. It's also something that ebooks can do which you cannot do with paper books (shipping costs can be a killer). I like it it because it doesn't take much work for an author to generate a unique, personalized momento for a fan.
BookieJar are calling their system "Autograph Now!", and it's open to all participating authors. I don't recognize the system they're using, but it appears to be web based. Authors can respond to signature requests from their account page and they can sign their name with a mouse or with a finger or stylus on a touchscreen enabled device. They also have the option of creating a generalized signature to embed in all their books.
This is strictly a signed ebook system, and that's not my preference. I like to keep my autographs in a collection separate from my ebooks. But it is a step in the right direction.
BTW, I expect an ebook autographing system like this one to show up in the Kindle Store by the end of the year. I don't know how many authors will participate but I think it will be there.
If you want to be free of Amazon, you might want to look at the platform independent Kindlegraph. It's in the process of launching under a new name, and it has over 1500 authors participating already.