Trademarks are not verbs.
http://www.adobe.com/misc//trade.html#photoshop
To some extent I can understand what they are saying in order to make photoshopping into a generic term for image editing.. but on the other hand I find it a bit pretentious.. but I guess in here we're used to playing with words anyway.. Wes sig "Verb that Noun" comes to mind 
And to make it a bit more fun:
http://digg.com/tech_news/Adobe_uses_photoshop_as_a_verb_ON_THEIR_OWN_SITE
uhm.. carry on...