Many of them are - some are just integration companies that purchase through Adobe (and one actions package is listed there as well).
And, of course, adobe.com shows up only on the second page.
Gotta love google's ranking system...
No you can get the CS6 upgrade from an official Adobe authorised distributor...but it seems most all of the ones listed in your google search are bogus!
I also thought that upgrades might only available through Adobe.com because of the following phrasing under the Buy / Try button on the Photoshop product page:
“Upgrade now. Individual CS upgrades only on Adobe.com.“
Does “Individual CS upgrades” mean that Creative Suite Version 1 upgrades as opposed to CS2, CS3, etc, or upgrades of all the Creative Suite products bundled together—upgrades of one version of the Suite to another version, or upgrades for individual products that are part of the Creative Suite—upgrading just Photoshop that was part of a previous version of the Suite, or upgrades from individual products (e.g. Photoshop) to the Creative Suite of products, or Creative Suite upgrades for individuals vs Creative Suite upgrades for groups?
I upgraded via the website, so I didn’t really bother to find out what the phrase, meant, but it wasn’t clear, either.