Sure can! They can share the same music, apps, etc. I have a WIFI ipad right now and will be getting the 3G version later this month. My wife and I will be able to share the same music and apps simply by connecting to the same computer with the same iTunes account.
MY question is this: when I get my second iPad, could i restore the backup of my first ipad to it right away so that my new ipad has all the same settings, mail, etc?