FYI -- Mugglenet has posted high-res version of the back cover of HBP

[allthingshp]

No: HPFGUIDX 132287

tonihollifield wrote:
http://www.mugglenet.com/viewer/?image_location=hbpbackcover1.jpg

Major Spoilers!
 
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It looks to me to be Ron, Hermoine, Ginny, and possible Cho (behind 
Ron) looking up at the Dark Mark over Hogwarts!


Karen:
> Other watching the Dark Mark hover over Hogwarts and my immediate 
> reaction is "OMG where is Harry"?  I do not for one moment imagine 
> that JKR is going to kill Harry off in book 6 so why isn't he there?


I think Harry is around the corner on the front of the book...not in absent on purpose or anything.
Also I was thinking that the fourth person we see behind "Ron" is maybe Dean...not Cho.

allthingshp