Another thread from today has a youtube video of what the hidden android stuff looks like. Unfortunately they rolled through the "All Apps" list pretty quickly....would be nice to see a list of whats in there, its very possible the Play Store is already there.
If its there, I believe you can access it directly through that All Apps list, to then attempt to download the APK.
It might be failing to install because "device is not compatible"....the play store reads a property from a build.prop file on the file system to determine if the device you're on is compatible with the app you are trying to download. If thats the case, only editing the build.prop would fix it, but Im not sure if you can edit it without being rooted (unless maybe the default install is already rooted since its a "pure" Android OS?)