The WordPress Foundation, operator of the WordPress open source software project, sued the owner of the WordPressHelpers.com domain name, alleging trademark infringement. In May 2015, the defendant brought an opposition proceeding at the TTAB, opposing registration of the WordPress trademark application.
Using a domain name that contains a trademark, in connection with educational or other services relating to the trademarked product, is probably an edge case. This may not be a straightforward or predictable outcome. It shows, once again, the difficulty of managing trademarks in the open source context.
Trademark owners who believe their marks have been infringed sometimes challenge the domain names via administrative processes that would only result in cancellation of the domain name, and sometimes take the broader approach, as here, of bring a lawsuit for trademark infringement in U.S. federal court.