Because of Android's open nature, it would be trivial to open up an entire ecosystem of sensors and data loggers that would integrate
I think it would be easy for Apple to match this: they can just add a USB host port to the iPad and allow apps to talk to connected devices. Almost everything today is USB-based.
Apple just does a little step at a time instead of completely opening the barn door as the first step.
Agreed. I don't see why Apple would reject apps that connect to external sensors. There are already many such apps that use Bluetooth (eg Wakemate) or the headphone jack (eg Square), although getting approved to link up with the bottom port is supposedly a pain. If you want to take advantage of the closed nature of Apple's platform, you have to push the kind of apps they don't like. So far, that's mostly just home screen customizations and pirated games, I guess. Google Voice was looking like a killer app not-available-on-iOS but Apple backed off of that one.
I think it would be easy for Apple to match this: they can just add a USB host port to the iPad and allow apps to talk to connected devices. Almost everything today is USB-based.
Apple just does a little step at a time instead of completely opening the barn door as the first step.