I think we'll see two levels of iPad 2.
iPad 2 Good: 1024 x 768 screen (approximately same price as now)
iPad 2 Great: 2048 x 1536 screen (significantly higher price. +$200)
iPad 1: Still on sale for at least a few months at a slightly lower price.
(-$75?)
To those raising the issue that Apple doesn't want to change the screen resolution because they have standardized on 1024x768, recall that iOS is resolution independent. This means it works sort of like your printer. You can print something in draft mode or you can print in super fine mode. You get the same result either way, but one is sharper. The same with iOS. As you change screen resolutions the layouts are the same, but there is the possibility of making things sharper and crisper.