The Digital Curation Centre has released "Archiving Web Resources," as part of its DCC Digital Curation Manual.
Here's the abstract:
The World Wide Web is among the most important information resources, and is certainly the most voluminous. In a relatively short time, it has become a vital medium for a range of academic and commercial publishers. However, until recently, little effort has been directed towards ensuring the long term preservation of the digital assets that reside on-line. The web's dynamic nature makes it prone to frequent changes, and without a means for capture and preservation it's likely that vast quantities of content will be lost forever. Since the web is home to a vast range of materials with widely varying characteristics in terms of formats, scale and behaviour there are inevitable issues that must be overcome to facilitate their collection, management and preservation.