It appears that a number of html pages linked from the extended reference are missing from the arduino-0010 distribution. The ones I noticed were Volatile.html Const.html PROGMEM.html Mathh.html PortManipulation.html Include.html
I took a peek at the SVN repository to see how the reference pages were generated, but it looks like they're all checked in together as a single 'reference.zip' archive. The current version of the archive still seems to be missing the files listed above.
I know this probably isn't a big deal for a lot of people, since the reference is always available online but I work offline relatively frequently, and appreciate having the reference on my laptop. Thanks.