It may be frustrating for many PPC users but I can't imagine that many developers relish the idea of developing for the platform anymore. Personally I wouldn't even bother to try myself as I have no PPC hardware and no desire to go out and find used equipment. For a corporation new to the Mac platform it is even harder to justify.
I'd suggest a new Mac. I also understand if you don't want to hear that but the reality is the PPC world will die off rather quickly with little support coming after 2010.
Dave
If Amazon used Xcode, from what I understand, they would get the PPC binaries "for free" with virtually no effort on their part. Apple tried to make support for Universal Binaries as simple as possible since no one would actually 'want' to make separate code for both. I don't know if Snow Leopard has changed any of this, but with regular Leopard (which they must have been using when they started developing it according to the time frame), it should have been straight forward for Amazon unless they're using other developer tools. There's nothing special about their reader that would require any kind of specialization or optimization that they should support Intel only. It's not a video game.
You can argue PPC has declining relevance, but an old Powerbook would be ideal as a reader. My 1.8GHz PPC machine does most daily browsing/e-mail activities as fast as my MBP (I can't 'feel' any difference) so why should I upgrade before I "have" to? More to the point, an older Mac makes a great server machine (in my case it serves over 400 movies, 350 CDs plus singles and over 5000 photos around my house to multiple Apple TV units and other Macs/PCs in the house and is on 24/7. This is a task its suited for since a newer computer would probably be using its CPU for more intensive tasks. My PPC machine has a fast (100+MB/sec) set of SATA hard drives in it, which is more important for serving multiple rooms at once than the CPU (which still usually averages around 45-50% the power of one of the cores in my 2.4GHz Intel MBP (yes I could have got a dual 1.8 G4 as well if you want to complain about the lack of a 2nd CPU core) so it's not THAT slow regardless). So on the contrary, it's companies like Amazon that "couldn't be bothered" that make life difficult long before it should be. Most Mac owners expect to get MORE life out of their computers than a typical PC, not less. Worse yet, other than video cards, CPU speed increases on a single core level have been pretty slow to increase in recent years compared to the days of ever increasing clock cycles. We saw 3GHz over half a decade ago. Most Macs run closer to 2GHz than 3GHz so all the speed increases have been on the architecture and multi-core and multi-thread side of things. That's great for multi-tasking and "some" programs that are multi-threaded, but not much help with many other programs and the majority of games out there.
I think Apple has had to artificially "kill" older Macs (e.g. by not supporting them in Snow Leopard, whether it be any support at all or not using features like hardware video acceleration for H264, etc.) to try and force newer hardware sales. They do this with the iPhone OS all the time (no motion capture except the latest model despite the ability existing on older models; using 802.11N chips, but only allowing "G" operation for now so they can enable it in a future model or software upgrade, etc.) Because frankly, as most fan-boys like to point out, the Mac isn't a "gaming" computer and so short of heavy video editing and the like, the average Mac user doesn't NEED massive CPU and graphics features in their daily lives, making Steve's need for dough more difficult and heading increasingly into "gadget land" to find new sales and to attract new users to the Mac platform (Vista helped there too, but Windows7 will probably slow that down since it's a big improvement over the initial Vista).
In short, PPC is dead only because Steve doesn't want to sell it or support it anymore (since they want to sell new computers not let you keep using old ones) and companies like Amazon can't be bothered to support it. Mac Pro Quad PPC are still pretty powerful machines today. I'd be doubly irritated if I had bought one only to find I cannot even run a lowly book reader four and a half years after I bought it.
With the newer Macs, Steve found a way to FORCE upgrades and it's called the "battery replacement program". The average user who doesn't want to open their Macbook might find themselves with a dead battery and a company that refuses to replace it in the future (ala scratched iPads where you will be forced to buy a new one since they don't want to change your battery, but trade you entire devices for some stupid reason and don't accept the slightest defects for a trade).
