Well, according to the creator of Wordle:
Wordle is a toy for generating “word clouds” from text that you provide. The clouds give greater prominence to words that appear more frequently in the source text. You can tweak your clouds with different fonts, layouts, and color schemes. The images you create with Wordle are yours to use however you like. You can print them out, or save them to the Wordle gallery to share with your friends.
This is a snapshot of the Citrix Blog Wordle on 2008-08-19:
Images created by the Wordle.net web application are licensed under a Creative Commons Attribution 3.0 United States License.