From a new features overview of Autodesk Design Review 2010 (http://dwf.blogs.com/beyond_the_paper/2009/02/autodesk-design-review-2010-new-features-overview.html) comes the following snake oil claim:
Digital Signatures
To help secure your data, you can now digitally sign DWFx files.
As I’ve explained before, digital signatures do not provide data security; they simply authenticate the person that applied the signature. Digital signatures are a welcome feature with many potential uses, but data security is not one of them.