The Google cache date on most web sites have now been updated, after having not being updated for over a month. This is a rather significant update, I think, as normally the Google cache date is typically updated on a regular basis. But in the past few weeks, it had not been updated in over a month.
The Google cache date for my site, for example, has been updated on November 30th, and previously it was updated in mid October.
Typically, when Google will stop a service like updating the Google cache dates on sites, that could mean that there may be a Google update going on–or something related to it. For some reason they need to “stop” or “halt” one particular service (like the Google cache date) because that database or something related to that data is needing an update.
Here’s my theory:
Google halted the update of the Google cache dates on certain sites because the Google cache date is related to one particular ‘process’ of crawling sites. For example, it could be related to links, for example. Remember, the Google cache date is related to the disavow file: if you check the Google cache date of a URL that you disavowed, and the Google cache date is after the date you submitted the disavow file, then Google IS taking that URL into account (they’re disavowing it).
But, if the Google cache date on a URL that you disavowed is before the date when you uploaded your disavow file, then Google is not taking that URL into account (they haven’t disavowed it yet.
So, it’s quite possible that they halted the Google cache dates on pages for a period of time (longer than a month) in order to deal with disavow files (or maybe the disavow process needed to be updated).
It’s also worth noting that there are reports that Google is continuing to update their Google Penguin algorithm, some noticing that an update happened around November 27th and 28th.