We've previously talked extensively about one of Mozilla's core marketing tactics - search engine marketing. One of the questions we always come back to is: "what macro level effect does this activity have?" In other words, we know this channel is driving clicks and Firefox downloads every day, but is this effort actually aiding Firefox adoption in some way?

Yesterday, Net Applications released its latest market share report for May 2008. Firefox showed a nice improvement in the April to May timeframe, going from 17.76% to 18.41% worldwide market share. Net Applications provides their own interpretation here.