What exactly are you talking about, streaming movies like Netflix? Right now that option is only available to DISH customers. Perhaps in the future Blockbuster will make a Netflix type App so all the gaming systems will be able to stream movies too.
Actually, Blockbuster on Demand is already available on Western Digital WD TV Live media players.
I'd be surprised if they weren't working on getting this for other devices through firmware updates, etc, so I can't see why it wouldn't be something that will end up on consoles soon, especially after Netflix t'd off so many of it's customers.
Blockbuster on Demand is more or less like Vudu (already on the PS3) and Cinemanow (coming soon to the PS3), you pay for online rentals of single movies. So if that even comes to the PS3, there isn't much to separate from the other two services. The new Blockbuster Movie Pass is more like Netflix, but is only currently for Dish subscribers, but should be available to everyone soon...