I developped a simple test code that prints CPU and GPU devices supported on the host platform.
I used same hardware and I compiled/tested the same code on two different OS : Windows 7 64bit and Ubuntu 12.04 LTS with same version APP SDK 2.7
The CPU is recognized the same way on both, but GPU is not OpenCL capable on Ubuntu side ... however I installed the fglrx driver correctly (version 12.6) which shall be supported by APP SDK 2.7
I guess something shall be still wrong with my fglrx installation somewhere .... ???
As it's working on Windows 7, I guess my GPU HW is OpenCL capable (Mobility RADEON HD 4570)
(I attached the sample C code I use....)