The Librarian Loose on the Web mentions an article in PDFzone on the ability to convert a pdf document to an audio file. Using Scansoft software, it’s very possible. "By integrating RealSpeak text-to-speech technology—which ScanSoft acquired in its 2003 merger with SpeechWorks—into OmniPage, it's possible to make PDFs (or pretty much any document in any format) talk to you through your iPod. And that's not just electronic files: OmniPage can make paper (provided you have a scanner) or image PDFs—bitmap files of scanned text—into WAV files as well."

So you now it is theoretically possible to listen to research articles while commuting, jogging, etc. However, as the Librarian Loose on the Web points out, the opitcal character recognition softare may have problems with medical terminology and words unique to the health environment.

It would be itneresting to see how this works for scientific and medical literature.