The developers haven't released any official information
The Daily Build of Lubuntu 13.04 (Raring Ringtail) has also been announced by Canonical, alongside Ubuntu, Kubuntu, and Xubuntu.Lubuntu is a distribution that aims to be a lightweight operating system, which uses the minimal desktop LXDE and a selection of light applications.
The developers of Lubuntu 13.04 (Raring Ringtail) have yet to release any important details about the new distribution, but we do know what packages are included in the Daily Build.
Lubuntu 13.04 (Raring Ringtail) features Linux kernel 22.214.171.124.19, Abiword 2.9.2, Audacious 3.3.1, Chromium internet browser 22.0.1229.94, Evince 3.6.0, Mozilla Firefox 17.0 Beta 4, and Transmission 2.61.
The daily build of Lubuntu 13.04 (Raring Ringtail) can be found on the official Canonical website. Remember that this is a development release and it should NOT be installed on production machines. It is intended to be used for testing purposes only.