The KDE community today released the third beta of Applications and
Development Platform 4.13. With API, dependency and feature freezes in place,
the focus is now on fixing bugs and further polishing. We kindly request your
assistance  with finding and fixing issues.
A partial list of improvements can be found in the 4.13 Feature Plan . A
more complete list of the improvements and changes will be available for the
final release in the middle of April.
This third beta release needs a thorough testing in order to improve quality
and user experience. A variety of actual users is essential to maintaining
high KDE quality, because developers cannot possibly test every configuration.
User assistance helps find bugs early so they can be squashed before the final
release. Please join the 4.13 team's release effort by installing the beta and
reporting any bugs .
The official announcement  has information about how to install the betas.