Currently, the enterprise-level Adobe LiveCycle ES product allows users to embed advanced DRM restrictions to their PDFs - printing, copying, and time limits are all supported. A major component of this is a 'policy server' which can be set up locally or by Adobe to monitor the ongoing usage of DRM-enabled PDFs. The end user is notified via a dialogue box that the author of the file is monitoring its usage.

Given the explosive growth of personal publishing via the web (ebooks, blogging, etc), I think there's a great case for making these capabilities available to non-enterprise content authors. You could easily set up a web services situation that would allow a blogger to pay a monthly fee for the ability to monitor and better restrict his/her ebook usage.

Another example: a small business publishes a short guide/ebook that they wish to license out to other organizations. For a small monthly fee, the licensee can print as many copies as they want of the ebook. By allowing that licens