As you may have noticed, we had an upgrade from Adobe earlier this year, named CS5.5. Even though it wasn’t a major upgrade, not every Adobe application got an upgrade, i.e. Photoshop (among some other applications) doesn’t have anything new and it is not a Photoshop CS5.5.
There are some major changes just around the corner, that will change the way new versions (starting from what I understand will be CS6) will get upgrades. From what I understand, when Adobe release Photoshop CS6, you will need to have CS5 or CS5.5 to get an upgrade (you will only be able to upgrade up to two versions, so CS5->CS5.5->CS6. Correct me if I’m wrong.
From what I understand, if you do not have CS5 or CS5.5 when CS6 is released, you will NOT be able to get an upgrade… You will have to buy the full version instead, what for Photoshop would be somewhere around £700 in the UK ($700 in the US)…
What is suggested (not by me) is that people upgrade their CS4 to CS5.5 now, so next year they could get an upgrade to CS6. But then, will it come cheaper to pay for an upgrade now and then next year again? You judge it by yourself.
Another option you will have will be to pay subscription for Adobe software (monthly or yearly), which makes some sense to some people, people who don’t use Photoshop on regular basis as an example.