just being a little mischievous here - I found this on another copyright blog - the excellent 1709 blog which is a very useful fund of information and contacts. 

 

While on the subject of terms of use ... this Kat did not receive an e-greeting from the UK's Copyright Licensing Agency this year, though he assumes that it's nothing personal since he receives lots of news from the CLA.  One of the Kat's friends did however receive this year's greeting, illustrated above.  This friend, who prefers on this occasion to remain anonymous, wonders if anyone else noticed the little bit at the bottom left-hand side of the greeting -- the bit with the image of a small but unmistakably red bird, in the familiar shape of the Twitter bird logo.

Now, it's quite possible that the CLA has negotiated something with Twitter and that there is nothing untoward about the little red bird.  However, if you visit the web page entitled Twitter Trademark and Content Display Policy and scroll down to the logo's terms of use ("Using the Twitter brand and trademarks"), you will find the following list of no-nos:

"Don't: 

Use speech bubbles or words around the bird.
Rotate or change the direction of the bird.
Animate the bird.
Duplicate the bird.
Change the color of the bird.
Use any other marks or logos to represent our brand".

Red faces, anyone?