Ars Technica (rapidly becoming one of my favorite news and information sources) has published a guide to Creative Commons licenses and Creative Commons licensed images in particular. The guide is titled "Creative Commons images and you: a quick guide for image users" –
Here at Ars we're big fans of Creative Commons, both the idea behind it and the work that gets produced. As publishers, we benefit from Creative Commons in a number of ways—we look things up in Creative Commons-licensed Wikipedia (used with caution, of course), the Creative Commons-related policy issues that we cover give us a steady stream of great news content, and we make use of Creative Commons-licensed images in our news stories.
This last piece—the use of Creative Commons images—has historically been one of the trickiest issues for us to navigate as a publisher, given the number of different Creative Commons license types. Each Creative Commons license has its own set of restrictions, and, despite the fact that the license clauses seem fairly clear on the surface, it's not always obvious to us as end users what can be used where and for what purposes.
One of the most common copyright issues I have come across is copyright infringement through improper image use. People often tend to assume that because images are available online, they are freely available for their intended uses. This isn't always the case at all. As with most other forms of content, images found online are subject to their author's or licensee's copyright and permissible uses are restricted depending on the copyright owner's preferences. In other words, when you find images online you should assume that you need permission for most uses and that permission is usually given in the form of a license.
These licenses can be custom worded licenses (licenses in website terms and conditions tend to be good illustrations of these sorts of custom licenses) or they can be any one of a number of standard form licenses. Creative Commons licenses are freely available standard form licenses. The Ars Technica guide is an introduction to Creative Commons licenses and how to find appropriately licensed content. This will be particularly useful for bloggers and marketers so it is worth reading and even bookmarking the guide for later reference.
On a related note, if you are familiar with Creative Commons licenses, generally, you may also know that these licenses are localized for various countries and regions, including South Africa. If you are in South Africa and want to license your content using a Creative Commons license, consider using the South African version of the license. Its terminology has been adapted for South African law. You can pick a localized version of the license when you choose your license features: