This past weekend there was quite a bit of discussion around the "rev=canonical" proposal (see here) and how, despite the advantages (URL shortening) it seems to have there are still some downsides to be considered. Here's what some of the PHP community have been saying:

• Ben Ramsey:
  • A rev='"canonical'" Rebuttal
  • Summarizing My rev='"canonical'" Argument
  • Specifying rev='"canonical'" With HTTP
• Chris Shiflett:
  • Save the Internet with rev="canonical"
  • A rev="canonical" HTTP Header
• Marco Tabini: Rev=Canonical madness
• Evert Pot: rev="canonical" and url shortening
• Rob Allen: Shorter Link: A rev=canonical WordPress plugin
• Lukas Smith: rev=canonical
• Paul Reinheimer: rev="canonical" is moving too fast.
• Dave Marshall: Rev=Canonical and all that Jazz