Well I read when Intel first started putting its Atom chip in mobile phones that not all apps will work. And I also read that app devs have to compile the app differently. I don't think apps on android are pure Java are they?
As taken from
"The Android Native Development Kit (NDK) is a companion tool to the Android SDK. The NDK is a powerful tool for developing Android applications because it:
Builds performance-critical portions of your applications in native code. When using Java code, the Java-based source code needs to be interpreted into machine language using a virtual machine. In contrast, the native code is compiled and optimized into binary directly before execution. With proper use of native code, you can build high performance code in your application, such as hardware video encoding and decoding, graphics processing, and arithmetical operation.
Reuses legacy native code. C/C++ codes can be compiled into a dynamic library that can be called by Java code with a JNI mechanism."
So by the looks of it performance critical parts of apps are separated from the Java and compiled into native code