I've actually been thinking about this as well. I love Android, so naturally the idea of seeing a bunch of phones with it seems great. More developers interested in it, maybe more interaction with other phones because of the same operating system...
But like you said, hardware will be different on all phones. I have a feeling not every phone will have a touch screen, many will probably not have accelerometers, etc.
Hopefully, since it's Linux, it will be able to support many different hardware configurations so we won't have to worry about it. Also, as G1 owners, we have the first Android phone so we probably won't need to worry about it anyway.
What they should do with respect to apps is develop some sort of system in the Market where developers will be able to specify "system requirements" for apps, so that users will know which apps will and won't work on the phone. Also, the developers could maybe be able to write code in their apps to see if a user is running certain hardware (like an accelerometer for example) and if the phone doesn't have one, all features requiring it will be disabled.
I'm sure they'll think of something...