Simple, re-usable, un-loseable (critical for me, anyway)...very cool.
The Albatross Bookmark -- I may have to try some of these!
Of course, there are some drawbacks; if someone flips through your book, you'll lose your page, but as someone who tends to either slip little pieces of paper into books or (gasp!) fold pages, that happens anyway.
Now, will it mean I'll give up my Kindle? Not a chance. But then again, getting a Kindle (I'm not on my third e-reader) hasn't slowed down the purchase of physical books in my house one bit!