From Mandriva Community Wiki
Official Mandriva Sites
In order to avoid reinventing the wheel, you should know where to search solutions on other distributions' sites. Below you will find some links to get you started.
Fedora is a community project dedicated to building high-quality, 3rd party rpms, for the Red Hat Linux distribution. They merged with RedHat the 8 october 2003. They have mailling lists, and a Bugzilla. Red Hat Linux is the original distribution from which Mandrake/Mandriva forked. They also provide rpms, and it is useful to check their Bugzilla, and see their SRPMS. They also use a wiki. You can see Fedora News on http://fedoranews.org/colin/fnu/. A cvs server has been setup.
PLD Linux is a Polish linux distro that also uses RPM. They try to implement a clean distro, featuring some interesting concept, as explained here. They offer access to their cvs, and their Bug system.
Debian is a community based distribution, developed by volunteers. They use their own Bug tracking system, and provide their patches in the form of single gzipped files, on the packages pages. They also have an extensive document about the library policy, adopted by Mandriva Linux. More info can be found on their wiki. A script to split Debian patch is available on Debian Patch Splitter.
Ark Linux is a new distribution aimed at desktop users. They provide some software, like a control center. You can check their cvs, or their Bugzilla. The development version, called Dockyard can be found on ftp://ibibilio.org.