Dissying rate eh? OS 7/8/9 applications was supported in OS X through Classic Environment for over 5 years after they quit selling OS9. Then they quit supporting PowerPC in Snow Leopard. Snow Leopard is a 64-bit OS, kind of hard to install a 64-bit OS on CPU's that are not.
You're right, supporting 17 years of software for a big 5 years was mighty nice of Apple. Every K12 environment loved that, especially when they bought intel Macs and had to start throwing out 17 years of software.
There is one rather expensive K12 software title called SuccessMaker which had to be bought 3 times over in Macintosh schools in a 7 year period. Once for Classic OS, again for OS X with a rather horrific kludge to work under it, and a third time to adopt a web based version of it because the OS X version never worked right. The software licensing cost makes Photoshop seem cheap in comparison.
As far as I know, the Win32 application designed around Windows 98 still runs fine on Windows 7 64 bit.
This is not an isolated incident.
Schools who went and bought a rack and populated it with XServes are scratching their heads wondering WTF is going to happen long term. XServe is gone, OS X Server is going to be incorporated into OS X Lion, and Apple is dumping Samba and rolling their own SMB client. I'm sure that will be a really smooth migration from OS X Snow Leopard to OS X Liion, and Apple will fully support migrating over all the options in smb.conf with whatever they make. But remember what Apple says about OS X Server, "No IT Department required!"
Mac Software - Buy Mac Applications, Utilities, and Games - Apple Store (U.S.) Look at all the software which runs on OS X Tiger and below!
I can't believe they are still selling a "Wireless N" enabler for $1.99 on that webpage.
InformIT: Top Ten Highs and Lows of a Decade with Cocoa > Lows
Mac OS X 10.6 Snow Leopard compatibility table - Snow Leopard Compatibility