I downloaded a copy of the non-commercial version of the Intel C++ compiler 7.1 for Linux and was impressed by the number of optimisations as well as the performance improvements over gcc. Does anyone know if its possible to compile the linux kernel using it? The compiler seems quite compatible with gcc.

Things might have changed with recent versions, but last I heard, the Linux kernel would not compile with ICL. FWIW though, I wouldn't dare to trust a kernel compiled with this compiler though due to it's traditonal instability in compiled code. This thing is for milking the last drop of performance out of code in projects where speed is favored over accuracy and even stability -- definitely not something which would often be favorable in an OS kernel, and certainly not in any sort of production environment. It might be interesting possibility for a desktop system, but even then I honestly wouldn't bother.