The answer in the FAQ on the Autodesk web site is:
Yes. You can redistribute Autodesk DWF Viewer to anyone without prior approval from Autodesk, subject to the terms of the license agreement. The easiest way to share it with someone else is to include a short message and the URL when you send a DWF file. Here is an example: Use the free Autodesk DWF Viewer to read this file.
If you examine your license agreement (license.txt file gets installed) for Autodesk DWF Viewer 7.0, you will find:
You understand and acknowledge that this Agreement provides for the copying and distribution of the Software in its entirety and does not allow for partial distribution of any of the components (.dlls or other files) that make up the Software. Creating derivatives of the Software is strictly prohibited. Redistribution of: (i) the Software that is integrated with other technology as a component or standalone product and does not provide end user access to the complete Autodesk DWF Viewer install process, including this Agreement; (ii) incomplete, modified, reverse engineered, or otherwise altered copies of the Software, is not permitted and will result in termination of this Agreement, in addition to any other rights or remedies of Autodesk.
Based on the license agreement, a common strategy is for application developers to include DWFViewerSetup.exe with their applications and have their users run it as a prerequisite to installing their applications. The MSI file is also available. The ability to include the free Autodesk DWF Viewer with applications that add value to the DWF experience helps DWF go beyond the paper.