'Dotted' Backgrounds

Sorry if this has been asked before. I don't know what the effect's called, so it's kind of hard to search for it. Can anyone tell me how to get the dotted background effect found in these icons for Photoshop 7.0 or Photoshop CS?

icon 1, icon 2, icon 3, icon 4.

Any help, or direction to another tutorial would be awesome. The creator of these icons didn't have any tutorials about it on her LJ.

Thanks!