[chc]

That isn't an "Apple euphemism." It's a pejorative term much older than the iPhone that Apple's critics apply to the Apple ecosystem.

[eupharis]

The term has been appropriated.

John Gruber: http://daringfireball.net/2010/06/iphone_os_too_closed

Neven Mrgan: http://mrgan.tumblr.com/post/653708588/the-walled-garden

[mkr-hn]

I think I first heard the term used in the context of technology on Observers.net in reference to AOL, but it's probably even older.