Yahoo announced last week that the Ads for Adobe PDF Powered by Yahoo! service is now officially up and running. Website Magazine tried out the service a few months back and by all accounts it worked pretty well in terms of creating ad-enabled PDF's, managing them and yes, of course, monetizing existing content. Ads are displayed in a panel adjacent to content. See an example here - warning - you must have Adobe Reader 8, otherwise the ads will not be displayed. Problem? Yes, but that's just the beginning.
The problem with the program is not that the ads are not relevant (they most definitely are) or that the potential payout is not high enough to offset the cost of integrating PDF's into your existing content. The problem is that most people (and since we've tried this on our own site I'm speaking from first hand experience) is that few people choose to download content in a PDF - for many it's just simpler to print out an article or read it online. If no one is downloading the PDF content, fewer people will see and click on the ads, The other downside is that as a publisher of content, I want people to read the content, to act on the information, even share it with others. They can't do that at the rate I want them to if they are constantly being presented with advertising - regardless of how seamless and non-obtrusive it appears to them.
If you have not been dissuaded from using the program, you can sign up here. For more information, check out the Adobe blog.