With a tweak here and a bit of tuning there, the Apple TV is going from the best available media extender to becoming to movie watching what the iPod is to music: the device that defines a category.

First, you can now rent and buy movies for Apple TV on the same day that they’re released on DVD. Numerous studios including 20th Century Fox, Walt Disney , Warner Bros., Paramount Pictures, Universal Studios, Sony, and Lionsgate among others have finally free Apple from the silly restriction that Apple couldn’t sell or rent movies until they had sat in movie rental stores for 30-days.

You can also buy movies now while you’re sitting in front of your television. It’s a handy little feature if you, like me, finding yourself wandering the virtual shelves of the iTunes store on your television.

Now I can look at the just released movies, rent or buy them or more than a thousand others already on the iTunes store, and the only thing I need to move is my finger on the Apple TV’s tiny remote or, in my case, my Logitech Harmony 676 remote. In short, it’s a couch-potato’s dream come true.

Are either of these changes all that big a deal? While I think that the movie studios putting the Apple TV sales on the same footing as DVD sales is a very important business move, neither move in itself makes a major difference for Apple TV users. That said, it’s these small moves that are making the Apple TV as necessary a part to a home entertainment center as a DVD-player or DVR (digital video recorder).