Note: I am not an attorney. The following are generalizations only based on my study of copyright law and are not meant to be construed as legal advice. If you have a question, consult a competent attorney specializing in copyrights and intellectual property law.
This does not mean that you can't use it. It just means that you have to ask first--just as with non-virtual materials. The good thing is that it's a piece of cake to send email to someone and ask permission. So, if you see something on someone's web site that you'd like to use, send an email and ask. This goes for icons and gifs as well as words.
copyright 1996, Martha Beth Lewis