Update: James "Snuey" Allen, who originally sent me the information about this, just forwarded me the following email from David Schmitt (Mac OS Product Marketing Manager): "I'm not disputing James' recounting of his conversation with the phone rep, but it is absolutely categorically untrue that we have dropped the requirement of proof of ownership of 7.5.x in order to qualify for the 7.6 upgrade price. I want to apologize for the confusion. We're looking into the matter and will correct the source of this misinformation!"
Update: Who knows what's going on here exactly? Jeff Schatz has just written with the following info (confirmed by others): "I called Apple to order OS 7.6 and it was $69.95. The operator will ask what version you currently have as indicated by what it says in the 'About this Macintosh' window. Say 7.5 anything and it's $69.95."