I don't even own a PS3 but I thought the free offer was reported to be for the PS3 version as well. I saw an online video of some Sony people demoing it somewhere and I'm pretty sure they mentioned that it would be in free preview for the first week.
Although I have no intention of signing-up for DirecTV (not unless they offered a Sunday Ticket only package) I would consider signing-up for Sunday Ticket on the PlayStation Network. However, ST had better look great and work just as well if I am going to fork-over $339,96 for the service; it had better be HD quality and no lag when switching games. That's why many of us PS3 owners are wanting to see the "Free Preview" being offered by DirecTV/Sony. It's similar to free samples given out at Costco...they hope you enjoy the product and place one or two of them into your shopping cart.
This preview weekend is costing DirecTV nothing. In fact, it costs them less than it does Costco and their vendors to pass out samples of pizza, bagel bites, etc. Since DirecTV hold all the distribution rights for NFL Sunday Ticket they will be making $$$ from the Playstation folks who do not D* customers. I have no doubt D* will make at least 50 million by putting ST on the PS3. However, they're not going to make $339.95 from me unless I see a "Free Preview".