Even with everything we learned from the Screwup Of The Century — including the "alien autopsy" Gizmodo performed on the misplaced iPhone — there are still a whole bunch of X-factors surrounding the coming 4G, not the least of which is the rumored 960×640 screen resolution. (Giz's post-mortem noted a nice, sharp screen, but their inability to boot the remotely-wiped phone precluded any other evaluation.) Indeed, the latest rumor to waft through the Intertubes is that the 4G will borrow a page from the Zune playbook and call itself "iPhone HD."
Now obviously, higher resolution in general is a good thing. Otherwise, all those monstro flat-screen TV's and gazillion-megapixel digital cameras would be collecting dust on the same shelf as the Lisa and NeXT.
So why should higher screen resolution — on a screen, frankly, that's not much bigger than a playing card — matter to you?
John Gruber at Daring Fireball — who first broke the 960×640 rumor months ago — would be happy to tell you why. In short, the average PC computer screen has a resolution of 72 dots per inch. For most web graphics and image files, that's fine. But by comparison, printed material — post-Laserjet and certainly post-PostScript — requires at least 300 dpi for acceptable quality, and 600 dpi is more like it in the publishing big-leagues. Graphics-happy Apple hardware, ranging from MacBooks to the iPad, bump their rez up into the 132 dpi range — better, but still lacking.
The big surprise? A standard iPhone, with 480√ó320 resolution on a 3.5" diagonal screen, works out about to about 162 dpi. That makes for some pretty crisp graphics, compared to its big brothers, but it still doesn't compare to the printed page. (By the bye, a Nexus One runs 800×480, or around 250 dpi — which is approaching print quality — but is done in by its lousy screen font as well as the screen's lack of crucial sub-pixels, which reduce the "true" resolution.)
Which leads us back to the 4G. Double the pixels of the 3Gs means double the resolution: over 320 dpi, which is true print quality. Which is gonna look friggin' gorgeous. The only question now is: will developers using the new OS 4.0 SDK be able to harness all that added resolution? And how soon before Cousin iPad stamps its little feet and whines "I want a better screen, too!"?