I read it differently. If you've already got stuff listed elsewhere, I wouldn't take them down to list them. But to take a brand new story and put it on there, you're just promising to be exclusive for 90 days. When the 90 days are almost up, you can choose not to renew the Kindle Select and it goes to being a normal book, then you can list your book elsewhere.
They're just trying to hit on being the first one to sell the digital copy of your book. You can keep selling print copies elsewhere. You just have to remember to click don't renew or whatever after the 90 days so you can then list on Smashwords or wherever.
Also, it looks like the 5 days free advertising, is them giving your book away for free for 5 days. During that time, your book is taken off the lending queue, which means you don't get any money during those 5 days.
It looks very interesting, but I don't think I like the exclusivity thing. Especially since the only people that can get it for a loan are the ones that have a registered Kindle. So if you use the computer version, you can't borrow it or nothing
