http://www.pcworld.com/article/173074/bings_biggest_enemy_in_search_wars_hint_not_google_exactly.html

From the article:

"It won't be clear for some time whether Bing's attempt to grab search engine market share from Google has stalled, or even gone into reverse. The September numbers from Web metrics firm Net Applications show a slight drop in Bing's global market share, although Google's whopping share of the pie – still north of 80 percent – dipped a bit too.
....."