To reproduce:
1. Open attached the 'repro.zip'. It contains a script that has a parent and child classes. The parent class has the Serializable attribute
2. Build & run for WP8, development build
3. Notice the exception in the console:
"A script behaviour has a different serialization layout when loading"

Explanation:
The project has a different serialization layout for the editor and WP8/WSA. There were variables under the UNITY_EDITOR define, which caused the errors.