engine - 3:49 pm on Nov 1, 2010 (gmt 0)
Guidelines On Twitter Trademarks [support.twitter.com]
This document is designed to help you use our marks without having to worry about negotiating an agreement with us or talking to our lawyers. If you’d like to make any use of our marks that is not covered by this document, you must contact us at trademarks at twitter.com.
This is a useful document describing use of twitter trademarks and logos.