You can use Qemu to emulate different processors. Currently it is supporting the emulation of x86, PowerPC, SPARC, ARM, Microblaze and, with external patches, Z80 and HP PA-RISC. Itanium seems currently not to be available.
But keep in mind that emulating a different processor-architecture is really slow, even if you have a really fast processor. If you only want to do that because of compiling for a different architecture I would recommend a cross-compiling environment.