I'm not sure how many have noticed this, or how many it might affect. Adobe is changing their upgrade policy for Photoshop and some other applications in the CS suite. See http://blogs.adobe.com/conversations/2011/11/adobe-creative-cloud-and-adobe-creative-suite-new-choices-for-customers.html
Previously you could move to a new version of the software via the cheaper "upgrade" option if you were currently running the same software within 3 versions. Therefore when Photoshop CS5 came out you could "upgrade" if you were on CS2, CS3 or CS4. If you were on CS1 you had to pay the full amount for the new software.
Now you will only be able to "upgrade" if you are on the previous version of the software. This means that when CS6 comes out next year you must already be running CS5 or CS5.5. When CS7 comes out in mid 2014 - and Adobe has confirmed that releases will be regularly scheduled from now on - you will only be able to upgrade if on CS6 or CS6.5.
Now I'm still running with CS3 so would need to upgrade to CS5 before upgrading to CS6. Each of these upgrades might cost me almost £200 and if I don't do this then paying for the full CS6 might cost nearly £600.
There is an alternative, and this would probably be Adobe's preference - which is to subscribe to their Creative Cloud, at probably £50 per month. Doing this would provide a more regular income for Adobe. It would also take out the companies in between that sell their software - my last upgrade came from Amazon as it was cheaper than direct from Adobe. Of course you would get a lot more software for your money as you get access to everything in their Master Collection. However I'm sure I don't need Illustrator, InDesign, Flash, Fireworks or most of the rest of this package.
There is a special offer at the moment from Adobe where you can get 20% off the upgrade to CS5. So it looks as if I have until the end of December to decide what I'm going to do.