Used in modern consoles yes mainly, but there are older ones. x64 is the 64 bit extension of 32-bit x86. The PS2/PS1/PSP used MIPS, the N64's NEC was based on MIPS. Older 8/16 bits are based on Motorola 68000s, Z80s etc.
The cell is a hybrid--it's main PPU used PPC code, but the SPUs are...