The US court of appeals has ruled on a case involving the open source Artistic License finding that it is indeed a valid license.  The key to this is that the court ruled that the copyright provision of this open source license is enforceable.  Precedent is key in US law and since there have been few, if any, cases testing open source licenses this ruling establishes a precedent that will be used to defend all future open source copyright issues.  In essence, this ruling strongly supports open source licenses and therefore the software that is protected by them.  This is a great day for open source and even though this covers just the artistic license, it is easy to extend this to validate the copyright protections offered by the GPL, CDDL and other open source licenses.