Until now, people who downloaded non-LTS (long-term support) versions of Ubuntu were treated to a lengthy support period -- a full 18 months. Now, though, Ubuntu's technical board is shortening that support window to nine months, in the hopes that Canonical can assign its engineers to other projects. (If you look at the board's meeting notes at the link below, the group also agrees that most bugs get fixed within nine months anyway.) If you're wondering how this might affect you, the new policy applies to version 13.04, along with all future non-LTS releases.
Posts from Elizabeth Krumbach and Jono Bacon address the controversy over the community’s role in developing Ubuntu.