Lucent Public License
While the Lucent Public License is not one of the more popular open-source licenses, a number of products have been released under it. It has been approved by the Open Source Initiative. The Free Software Foundation states:
“This is a free software license, but it is incompatible with the GNU GPL because of its choice of law clause. We recommend that you not use this license for new software that you write, but it is ok to use and improve Plan 9 under this license.”
The clause in particular that causes it to be incompatible with the GNU GPL is "This Agreement is governed by the laws of the State of New York and the intellectual property laws of the United States of America."