There's an even faster way than sjwright's answer.

Type the windows key, then 'cmd', then press enter.

I really wish Windows 8 did a better job of teaching users, especially the quick ways to launch programs from the keyboard.

Win+X, C (or A if you need one as admin).

I have barely touched W8, but have they removed the Win+R run command? My go-to-prompt tends to be "Win+R c m d Enter" on XP and 7 (and "Cmd+Space t e r Enter" on Mac OS X).

On 8, I can do Win+R powershell or Win->type powershell, hit enter and be going even faster.

It still exists, unchanged.

Win+X then C for a Command Prompt. Or Win+X then A for an Administrative Command Prompt.

WIN + X, C

Right click the start menu in Windows 8.1. There is a command prompt (and admin command prompt) option.