I've had an impression that because of Android's abstractions you didn't have the same "bare metal" access, such that scripting languages have to be run inside a container app: http://code.google.com/p/android-scripting/
Your impression is wrong, you can get access to the full Linux shell.
It depends on what you want to do. Scripting Layer for Android is about letting scripting languages access Android APIs and services. In that case, you need some sort of container / runtime to talk to the rest of the Android/Dalvik world, but there's nothing that prevents you from getting at the bare metal, if that's what you want to do.
What are you basing that on? You can easily install Unix tools on Android devices. Here's a complete development environment that doesn't even require rooting: https://market.android.com/details?id=com.spartacusrex.spart...