7z comes to linux and is very handy. But if it is intergrated into tar one can preserve all file-specific information such as ownership, perms, etc. Which is very important. It is doable:

tar cf - /foo/bar | 7z a -si archivename.tar.7z

Another example, to list files in a 7z archive:

7z x -so archivename.tar.7z | tar tvf -

Handy!