Jean,
Are you sure you are looking for Web Services, I would suggest you start with some text on RSS (Really Simple Syndication).
I haven't seen any books on RSS...hmmm, but the RSS specification is available at
http://blogs.law.harvard.edu/tech/rss and a lot of sites publish content with it (
http://news.com.com/2009-1090_3-980549.html?tag=ne.ft.si.rss). Most blogs and portals use a version of RSS for content (Slashdot among them) without the a Web Services infrastructure! This content can easily be moved to different device footprints.
Once you have your basics in RSS, step back and decide where you want to go and maybe Web Services will fit better into your idea.
Just a few thoughts :-)