Odds are good that if you’ve used the Internet at all over the past year or so, you’ve seen this icon:
People use it all the time to display their tweets from Twitter. There’s only one problem: It’s copyrighted!
The icon belongs to a Twitter-specific application for Mac OSX called Twitterrific, and once I’d learned that it was copyrighted, I emailed to request special permission to use it anyway and Anthony Piraino with Icon Factory replied:
There is already a high level of confusion regarding the corporate identity for Twitter with the Twitterrific application icon of the blue bird and your site would only add to that. We are currently in the process of contacting sites that make use of the bird and requesting they stop.
Anthony added that he regretted not being able to approve my request, but asked for my understanding in trying to contain the growing misuse of their trademark. Although I’d much prefer using their icon to the icon Twitter itself uses, I completely understand and have agreed to not implement it in future blog theme designs. Furthermore, I’m letting my readers know they need to stop using the Twitterrific icon as well and find another metaphor to use.

There are many other icons available:
http://www.noupe.com/tutorial/20-twitter-status-design-tutorials-icons-wp-plugins.html
I wish more people would be as respectful. I know not everyone is a designer, but come on….don’t use a copyrighted icon!
Also, when you get a reply like that, you are much more likely to comply.