Here is a query that illustrates an interesting phenomena in Google's search results dates:
Try the query: site:cnn.com
The second result is for the url: money.cnn.com/ - 65k - Nov 28, 2005. However, if you look at the cached copy it says the page was retrieved on November 26th.
Now, I noticed that the leading store of the page is "The race is on". So I try my second query: site:cnn.com "the race is on" . The fourth result is for the same url: money.cnn.com/ - 63k.
Quite interesting -- the size of the page is 2k smaller and the date is not displayed. These results a different, despite the url being exactly the same.
It is also interesting that Google seems to only show dates next to content that is very recent, in these results, anything purportedly indexed in the past two days. Therefore, it appears that when I execute the second query Google recognizes the indexed date corresponds with the cached copy date of Nov 26th because it does not display the date.
The question is, why are these two queries inconsistent with the date of the content?
One hypothesis that I have is that the first site: query without a query term returned a generic summary that was generated from content different content from the second query. Perhaps the first summary was generated from data stored in the recently updated index? The second query contained a term and therefore required a dynamic snippet to be generated, perhaps from the same server that generated the cached copy? This would indicate that there is a significant amount of lag in the latest copy of content being propagated to cached content servers, at least in some cases.
Anyone else have a theory they would like to share?