Gateway Pages Prevent PDF Shock (Alertbox). Jakob Nielsen's followup to his piece on how evil PDFs are on the web. Quick quote summary:
Websites use PDF despite its weaknesses because it supports ease of posting, even as it denies ease of use. ... It's actually not very expensive to, say, create a set of Web pages for annual report information as long as the Web design is done while the annual report is being written. The cost comes when companies have a glossy annual report already finished and then say, 'Webbify this.' ... Rather than force it to solve problems that it's much less suited for, let's reserve PDF for what it's good at: printing. It's no disgrace to be the world's greatest solution for a single problem, especially one that's as common and important as printing.
I'm not big on gateway pages; since as a user I know what I'm doing (I am frequently reminded that I am not an "average user" and I should probably explain what the hell I'm talking about). I prefer a less involved and more realistic solution of ensuring links to PDFs are clearly labelled; or preferably the PDFs don't exist in the first place. If you take content to the web, use a web format. PDF is not a web format. Simple.