Canonical will have two big announcements in April, one regarding the launch of Ubuntu 14.04 LTS (Trusty Tahr) and the second one concerning the end of life for Ubuntu 12.10 (Quantal Quetzal).
The Ubuntu developers have changed their policy regarding the support period of non-LTS versions of Ubuntu, starting with the 13.04 build. This created a strange situation where Ubuntu 13.04, which had nine months of support, reached end of life before Ubuntu 12.10, which was the last one with 18 months of support.
Canonical realized a while ago that the support period for its Ubuntu operating systems was too long and the developers had to devote a lot of their time to support duties instead of using that time for innovation and progress.
A new support period of only nine months has been devised for Ubuntu operating systems. The developers increased instead the support period for the LTS versions (long-term support) to five years for both the desktop and the server versions.
The upcoming Ubuntu 14.04 LTS release is the first in the series to benefit from this extended support period, which means that it will be discontinued in 2019.
The final date for the Ubuntu 12.10 EOL hasn't been set yet, but it will probably be after the big April 17 launch of Ubuntu 14.04 LTS.