They have an article about some kind of dynamic Animated desktop they say they are working on for Leopard. Some people say "Active desktop seems nice, if for no other reason than it might do away between the abrupt differences between login screen, screensaver and such versus the desktop." But is this really as big a problem as they make it out to be? They make it sound like you are abruptly thrown out into the cold traumatically. Personally I don't think the login screens on Any OS are that animated\dynamic. Sure you might get icons changing size and sliding around but the desktops themselves are already getting similar animations when you do certain things. Screensavers I might give you but the rest... nah.
I say If this is anything like Quartz Composer files as desktops which you can already do on OS X if anything it'll take more resources than a static picture. And we wont be able to point to this as an advantage over windows because
they are already doing the same thing. This even includes the dynamic stuff... (like stuff that happens at certain times in the day). Sure if it's true what stardock says about video cards handing the whole thing it might work ok but... it probably won't save RAM (video card or otherwise) unless it's simple solid colors. You still have to store what you generate somewhere. This is not magic.
Even if we had this and it worked great it better be optional. I still will probably want to use static pictures sometimes. Unless this can automatically procedurally generate any photo or character without loss of quality, or whatever I want then there still are plenty of static pictures that I would want to use. Sometimes you might just want a static picture or even a solid color so it wont be distracting.
I wouldn't mind if you could make a desktop wallpaper that is in different layers though so it can adjust itself to your screen size. The enlightenment people have been doing this for a while now. At any rate I don't think it's something that Apple should get a patent for.
Having a desktop wallpaper optionally change when you enter\exit certain programs might be a good idea. You could have whatever wall you want for regular times and then perhaps a solid neutral color for when you are working in photoshop\illustrator might be a good idea as well. I'm not sure if anyone else has thought of that yet. Having photoshop in a MDI window like in Windows might give a similar effect but I don't like that myself and would not like to see Apple go in that direction.