To determine whether something is novel, all published literature is (at least in theory) taken into account. But in fields such as computer science, few literature exists. This makes it a lot harder to determine whether a particular invention is truly novel.
Because of this, several patents have been granted for things that many computer scientists argue was already known before the patent was filed. However, without a publication showing the invention in the patent, dated before the application date, it is not possible to get the patent invalidated.
It is at this moment too early to say whether WWW-related patents (such as the Amazon one-click patent, or patents on methods for using stylesheets with Webpages) will stand up in court.
More information on patents, copyright, trademarks and other Internet-related law is available on Iusmentis.com.