That's what I was thinking, I've been using that in Chrome for a long, long time. But this is talking about a 'share' button directly on the web site, as in it's in the list of 'share' buttons like fb, g+, email and all the rest.

I'm not really following why anyone would want to do it that way, if you have a kindle and read web sites like that you likely already have the sendtokindle extension. This seems to just be adding clutter to something I already consider clutter. Guess I'm not the target market, as usual.