See this link for detail: http://www.reddit.com/r/anime/comments/29y8mj/my_summary_of_kawahara_reki_sao_panel_at_ax/
In short, that mean the sunrise studio 8 that responsible for producing AW season 1 is now occupied with Love Live and they cant have enough resource to produce another season of AW by now. Both the series' author Kawahara Reki and the series' editor from the series' publishing company have a high desiration on producing another accel world season but there simply don't have enough people and money and such in the production company.
See https://en.wikipedia.org/wiki/Sunrise_(company)#Studio_8 for more info.
And see http://yusaani.com/news/2014/07/06/8626/ for auxiliary source I used to make the above summary
new accel world anime announced, but most probably not season 2.