From MozillaZine Knowledge Base
Firefox 2.0 introduces Microsummaries for bookmarks — a way to extract a bit of information from a web page and display it in the bookmark’s title. This preference determines how often microsummaries’ target pages are re-fetched for new information. Microsummaries can override this preference by specifying an
Possible values and their effects
Number of minutes between microsummary updates for microsummaries that do not specify an update interval. Default is 30.
First checked in
Has an effect in