Since the iPad launch on April 3, TiPb's been getting tips about desktop/dashboard/widget-style apps being removed first from the iPad App Store, then from the iPhone App Store as well. There are a number of examples, some well known by now, some relatively unknown. The commonality between all of them is that they've tried to somehow make the iPad or iPhone into a Mac- or PC-like screen filled with mini-apps like browsers, email clients, calculators, weather, etc.
Some look almost exactly like Apple's Mac Dashboard, other like Windows of various flavors. Others don't look like desktops at all but rather place widgets on top of photos or other, more specific backgrounds.
Devs have worked around this by using a much more restricted metaphor, like a double tiled display, or by going the Jailbreak route, or they haven't worked through it and just gotten frustrated at the opacity of the App Store review process and not known how to proceed.
I can't claim any special insight or information on this, but my best guess is that Apple is removing (or advising they will be removing since not all of them have been pulled yet) the apps for the same reason they originally didn't include cursor (arrow) keys on the Mac. It's a pretty well known story and one that's been used a few times in different commentaries on the iPhone and iPad and Apple's direction thereof, but it bears repeating.
The Mac was the mainstream transition from CLI (command-line interface) to GUI (graphical user interface). People had to become comfortable using a mouse to drive the new interface, and Apple felt that if they gave them arrow keys users would just launch text windows, abandon the mouse, and revert to what they were comfortable with at the first opportunity. They'd never learn the new paradigm because they wouldn't have to. So, like the metaphorical bird, they pushed us out the CLI nest and made us madly flap our GUI wings (or risk crashing).
The iPhone and now iPad mark a similar mainstream transition from GUI to multitouch user interface (I'm not calling it MUI). The iPad's display is bigger, but Apple doesn't want it treated like an old-fashion PC or Mac desktop, and they don't want apps in the App Store that encourage users to treat the iPhone or iPad like desktops.
Developers who have invested time and money into building those apps get crushed, of course, and Apple really has to figure out a better way of advising people which apps are on the "unforeseen" list as soon as they can possibly foresee them. I'm not defending Apple's process or policy here -- as I said I have no idea if I'm even right about the reason -- I'm just trying to figure it out. Curation isn't bad, but bad curation is chilling.
Users also will no doubt be upset they can't get these apps, just as users were probably upset Apple didn't include arrow keys on the original Mac. I don't know if Apple realizes that and just banks on having enough momentum and cool tech that users will once again forgive an App Store removal in light of what still remains and is coming. (That bank of user good-will isn't limitless, however, and I certainly hope Apple realizes that).
[Yes, or Apple could be getting ready to announce their own widget platform for iPhone OS as a special feature for that large-resolution iPhone HD/iPhone 4G at WWDC 2010. Those types of things are always possible.]