When I bought the Pre and openned a new account with Sprint, they offered me a 10% discount if bought two accessories. I wanted the Touchstone anyway, so I threw in some screen protectors and the discount covered those.
Palm has introduced some pretty slick new tech with the Touchstone charger. The kit comes with the Touchstone and another back plate. It is necessary to switch out the second back cover because it has the charging contacts that the standard back cover doesn't. Another reviewer has discussed the charging time and apparently it takes longer on the Touchstone than with a direct cable connection, but for my purposes, I just leave it on the Touchstone overnight.
The sticky bottom of the Touchstone, modeled on the adhesive power of the gecko foot, does live up to the hype. For illustrative purposes I've enlisted the help of my dog. As you can see, she was felt her safety was never at risk while sitting under the Touchstone, which is stuck to the window! I chose not to charge the Pre in this location, however. I don't want to risk a dropped phone.