It seems that the problem of this thread is solved in the Unity 4.5.2 patch 2 released this week.
Now it runs OK on windows phone 8 emulator. Cool
However, when compiling, there is a warning log in unity
Windows Phone 8 doesn't support "System.ComponentModel.LocalizableAttribute, System, Version=2.0.5.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e". Used by "HutongGames.PlayMaker.ReflectionUtils, PlayMaker, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null". Context: "GetGlobalType" method.
UnityEngine.Debug:LogWarning(Object)
I don't know if it will be a problem latter, but for now, everything is ok. No runtime error.
I will try and do some simple tuto projects this week end to test more deeply.
Sincerely,
Jery