Its mentioned that CUDA 5 allows library calls from kernel Does that mean CUDA 5 can use thrust or STL inside device code then ?

Answer1:

CUDA 5 has a device code linker for the first time. It means you can have separate object files of <strong>device</strong> functions and link against them rather than having to declare them at compilation unit scope. It also adds the ability for kernels to call other kernels (but only on compute 3.5 Kepler devices).

None of this means that C++ standard library templates or Thrust can be used inside kernel code.