Do Unity3d maintainers plan to support Linux(at leat Ubuntu)? I mean SDK’s and tools to developers.
Unity Technologies still do not provide a Unity Editor for Linux, but it can still be run on Linux using Wine. See the community set up wiki page - http://wiki.unity3d.com/index.php/Running_Unity_on_Linux_through_Wine
Otherwise you may set up a Mac or Windows Virtual Machine on Linux to run the Unity Editor.