To be fair, the dropping of support for Rosetta (Power PC emulation) was announced well in advance, and there are several posts around that show you how to easily check whether any programs you've got installed are Power PC. Several 3rd party software vendors have been very slow in updating their software to universal or intel only binaries.
My Spyder 2 Pro won't support Lion, but I can either run it with some alternate software, or create a virtual machine running Snow Leopard and do the monitor profiling that way.
Folks had exactly the same issues going from XP to Vista due to the change in driver model.
It always pays to wait a while after upgrades like this, and to read the forums to gauge the likely side effects and gotchas.
2F/2F: if you are downgrading, you need to do a clean install, or install to another disk (you can choose which disk to boot from at startup). If upgrading, I've just done straight upgrades or archive and re-install. It always pays to run a permission check first, and make sure you're not running any "hacks".