Yep, they're very minimal. Minimum requirements should be based on what you want to do with it, and how hard you want to push it.
If you need to scale hardware according to traffic - more traffic spawns more processes (depending on the configuration e.g. prefork/worker) - then you'll require more memory. If you're running intensive applications, like PHP scripts, then you need to scale for more CPU power. That's a very general rule though.