The new Mixxx's development team has recently released milestone 1.5.0. Adam Davison, the new maintainer, announcing the release:

"The first release in the 1.5.0 series is now available for Linux, Windows and Mac Intel platforms.
It represents nearly two years of development since the release of 1.4.2 and includes major changes such as the introduction of pitch-independent time stretching, a feature not available in many commercial packages.
We are aware that the build system for linux is currently a bit problematic, we apologise for this and are working on it as a matter of urgency. We recommend the binary package for now on linux. Hopefully we've got the library dependencies right, if they don't work for you, let us know."