Let's say you want Apple to release a new, all-widescreen laptop lineup (except for a 12" XGA or two). That includes pscate's little drool-worthy widescreen 14.1"
, which Apple definitely SHOULD make and offer in a low- and high-power config. They could make a killing vs. the weak current 14" iBook offering.
You can either go for 100 ppi, give or take a little:
14.1" 1152x768 (98 ppi)
15.4" 1280x800 (98 ppi)
17" 1440x900 (100 ppi)
If this is what they decide to do (the most likely scenario until a resolution-independent OS becomes fully implemented), then they will probably end up sticking with a 1280x854 screen resolution. No point in REDUCING the resolution. The only catch is that 1280x800 is a standard resolution for 15.4" screens and 1280x854 isn't (although Apple is already using it so there shouldn't be a problem).
Or you can go for 110 ppi, give or take a little:
14.1" 1280x800 (107 ppi)
15.4" 1440x900 (110 ppi)
17" 1600x1000 (111 ppi)
These could get hard to read but on the other hand they'd be very sharp and I bet they'd be quite usable.
Or even higher but it would be probably way too hard to read at this point:
14.1" 1440x900 (120 ppi)
15.4" 1680x1050 (129 ppi)
17" 1920x1200 (133 ppi)
Those last three are certainly too high. This DEFINITELY won't come out of Apple until they've worked out an elegant solution for increasing sharpness without making text unreadably small.
By the way, the Sony Picturebook has a resolution of 1280x600 on an 8.95" screen. That's a little over 21:10 aspect ratio, and 158 pixels per inch. But that's a bit different because it's not a primary computer that you'll be using for hours like an iBook or PowerBook is.