I wouldn't really say it pushed innovation forward. It's a mac with heavy specs. The only thing innovative about it is the enclosure -- which, while novel, isn't terribly noteworthy.
I have to disagree. There's a couple of things that drive innovation, like the storage on PCI-Ex bus, and the fact they cram 12 Xeon cores and 2 high-end GPUs in a can and still manage to air cool it. The fact there's a good amount of high-end specs in a totally new form factor is what makes it interesting for me.
PCIe storage has been available for PCs for quite some time.
12 Xeon cores on air.. do you think servers liquid cool these chips? Of course they cool them with air, that's how they're designed to be cooled.
I am impressed they crammed it all into a package that's only 10inches tall - but this is completely at the expense of modularity and expandability. You can't easily throw a new hard drive or GPU in this new configuration.
You can make the argument that Apple's biggest triumphs haven't been hardware innovations but commercial and usability ones. People aren't necessarily concerned that Tim Cook can't make a better desktop, but that he can't concieve products that leapfrog entire markets and industries like the iPod, iPhone, and iPad did.
Some of the biggest innovations that Apple made, IMHO, were pricing related.
The push to mandate unlimited data with every iPhone (and make that data plan $20 with 200 SMS) was critical to the iPhone's success - for me, coming from the Palm platform, it was simply amazing, while one the road, to go to the App Store, download an app, and in seconds be using it. Wouldn't be possible for most if they had to have a conversation with AT&T for 30m to add a data plan prior to doing the above.
Also, the innovation with the iPad to allow you to sign up for the 3G anytime pre-paid was incredible.
