>>172
glut32.dll の添付ドキュメントにちゃんと書いてあるよ？
曰く、パブリックドメインではないが、ライセンス料無しで配布して構わない。

原文
COPYRIGHT:

The OpenGL Utility Toolkit distribution for Win32 (Windows NT &
Windows 95) contains source code modified from the original source
code for GLUT version 3.3 which was developed by Mark J. Kilgard. The
original source code for GLUT is Copyright 1997 by Mark J. Kilgard.
GLUT for Win32 is Copyright 1997 by Nate Robins and is not in the
public domain, but it is freely distributable without licensing fees.
It is provided without guarantee or warrantee expressed or implied.
It was ported with the permission of Mark J. Kilgard by Nate Robins.

THIS SOURCE CODE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

OpenGL (R) is a registered trademark of Silicon Graphics, Inc.