Let me start by saying I hate staging and live environments. When I worked in a more traditional WCM industry these were the necessary evils of systems that created massive static sites on fixed schedules. SharePoint allows Web Content Management Publishing in real time. Real time changes are better. If anything the effort to fix a single page in real time simply by changing and approving a single page in SharePoint compared to the need to order a new publishing of an entire site should make any business see that real time WCM with strong approval is the way to go with SharePoint.
BUT, I have found that some Enterprises have evolved to a point they need the old staging and publishing environment to meet a set of requirements. This is entirely pointless in SharePoint since SharePoint publishing works with server side updates rather than publishing flat files.
But you can create a staging and live environment with CodePlex's Content Deployment Wizard.
Microsoft MVP Chris O'Brien gives a very good overview of how the tool works.
Now I can't repeat enough that on a very deep level Content Deployment in SharePoint just to have a staging and live environment separate from the authoring is wrong. All Content Deployment does is makes a copy of the SharePoint site in a other Web Server. You can get the same level of publicising control simply by using WCM features in SharePoint without having to build separate environments.
So if you find yourself in a situation where you need to use Content Deployment you should be very firm why you need it and the business should be aware of the risks, costs, and benefits of not using it. I can't stress enough that SharePoint has changed the entire Internet game. Designers who used to have small sites they could work and play with now need to think in industrial terms. Things need to be supportable, sustainable, they must reduce carbon, storage and cost.