I have seen a few posts about it... looks like it is true.
Showtime Offer for Existing Customers
Showtime is currently promoting a nationwide campaign through October 31, 2007, and DISH Network customers will be able to participate in this offer and receive Showtime FREE for 3 months. Existing customers who don’t currently subscribe to Showtime can add it and will receive the promotional offer. They would need to call and cancel it BEFORE the 3-month period ended if they did not want to continue to receive the programming. If they call after the free 3-month period, they would be charged going forward.