CreativeCommons is a project by LawrenceLessig (and others). It's cool. 
For the record, the reason I'm archiving "bad stuff" about the CreativeCommons licenses is because if haven't thought those through as I really like CC.
For and against the CreativeCommons licenses:
DanBricklin has some interesting concerns about the implications of the CreativeCommons attribution license for casual publishers (eg. bloggers).
When you "warrant" something you are (from a lay person's viewpoint) guaranteeing the person using your work that you'll indemnify them against loss if you were wrong; i.e., you'll reimburse them for what they end up paying if they are sued. In this license, you are saying you have made "reasonable inquiry" to make sure that you have sufficient rights to what you are licensing to let others use it without paying royalties. If you put that license on your weblog, you are saying you've checked about everything, including quotes you've made, deep linking, images (including trademarks that may show in the background or people visible without a model release), sample code for patent infringement, etc., understand "fair use" law, and feel comfortable even if someone then went and put those images in a movie or something, or your sample code in a program and sold it. The standard for royalties and damages are different for different uses. (While "fair use" may cover material cited in commentary on an academic weblog, there are stories how even a TV in the background of a film showing a popular TV show requires huge royalty payments.)
This is different than many other licenses that many non-lawyers are used to. For example, the "Artistic License", used for many open source products, Perl, etc., has no such warranty about freedom from infringement. Dave's RSS license ends with "This document and the information contained herein is provided on an 'AS IS' basis and USERLAND DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS..."
Why is the Creative Commons license so strict? That's easy to understand and appropriate: They wanted to make sure that users of the work would have the easiest situation possible to re-use the material, subject to straight-forward restrictions. The burden of checking for rights was placed on the author so it only had to be done once in advance. This is similar to many book and other commercial contracts.
What the Creative Commons people didn't do, as far as I can tell, is make a set of licenses for the casual weblogger, who does not want to consult a lawyer before each post. The Creative Commons licenses say, in effect, "After checking, I guarantee no one will sue you if you copy my work, with some restrictions". What many casual webloggers really want to say is "I guarantee I won't sue you if you copy my work, with some restrictions".