Of course, the innards of the device are far more accurate than the casing. Most likely the case is a prototype case, and the device may not look anything like the device shown. However, Daring Fireball said "Apple is very interested in getting it back."
That sort of statement points to this thing being the real deal.
However, sources also confirm that the iPhone HD (or whatever it will eventually be called) has a higher resolution screen, a front-facing camera, a higher resolution camera with flash, and uses microSIM cards like the iPad 3G. It will also indeed have 80GB of storage, and the rumored ceramic glass back.
For those concerned about the durability of the glass back, Daring Fireball dug up an Apple patent application from 2006, for " high-durability ceramic enclosures. Glass-like appearance and feel but far stronger and more scratch resistant. And: radio transparent."
Three months or so to go until the next-gen iPhone launches, so expect more leaks like this one. Well, perhaps not like "this one;" if indeed a real "droppage" some Apple employee is likely sweating bullets today.