NOTE: This function is deprecated in WordPress 3.0
Summary: Returns an array of blogs ordered by the number of posts in each blog.
Detail: This function tests for the existence of a site option called “most_active,” the cached version of which is valid for one minute at most. If the most_active option is newer than sixty seconds, the site_option version is used. If the most_active value is older than sixty seconds, the database is queried for this information and a new value set to the site_option.
The $num parameter sets the number of active blogs returned. If the parameter $display is set to true, is it is by default, a series of <li>’s, each containing a link to and the name of each of the returned blogs is print()’ed for output to the web page.