Sucks for them, missing back to school is bound to hurt. Will also hurt their resellers that still have an inventory of current iMac's. A lot of people are likely to hold off on buying one knowing that something bigger and better is just around the corner.
Not much word about what the new form factor will be. Some rumours are that it will be an LCD mounted in a rectangular box. Bluetooth mouse and keyboard. If so, makes me wonder whether or not it could be considered somewhat a portable desktop. The current iMacs have a pretty heavy base, especially the 20" to counter the weight of the lcd panel.
Lots of mac users would also love to see a headless mac (ala Cube), but I don't think that is going to happen.
With the delay, you have to think a lower powered G5. I think the public will be disappointed if it is still a G4.
