If iTunes is truly the reason why Acer can't/won't compete, then probably the only company that may have a system to counter Apple would be Amazon.
MP3
OnDemand video
e-books
They would have to redo their Kindle lineup too, but it shouldn't take that much to come out with something more sophisticated than a Kindle DX with existing technology, or what was demonstrated at the latest CES. They would also have to tie everything together in a slick, pleasing package.
But, if Acer can't do it, then neither will Asus, HP, Dell, etc. Google's ChromeOS project and Android may help them, but they would still need some way to get the music, video, and ebooks to their customers.
Maybe Google and Amazon should form a "Tablet Alliance" to provide the OS, office apps, ebooks, music, and video for hardware manufacturers to come up with their own designs for tablets and netbooks.
So, that's what you're looking at with Apple. They have roughly a year to maybe a two year lead on any competitor. The real question is just how big is this market and do people really a "tweener" device at $500-$830 or just a cheap laptop, aka netbook.