I really want this, but I'm waiting for them to update the 11" version. Strangely, Best Buy, but not the Lenovo website, has an 11" sku with a Haswell chip in it, but no other upgrade, i.e., it weighs as much as the refreshed (slimmed down) 13" version and lacks the updated resolution and backlit keyboard. So I'm determined to wait it out. It can't be long before they give the 11" version the same treatment as the 13".
Speaking of disabling the keyboard, have you seen the Thinkpad Yoga that's about to be released? When that screen is flipped into tablet mode the keyboard tray raises up flush with the keys and the keys lock, so you have more-or-less a normal flat surface feeling on the back of the tablet. It's pretty freaking ingenious, but it's a bit thicker and heavier than the regular Yoga.