widely used until there is an "lzip" which does the same thing. I actually started the work of adding LZMA support to gzip, but then realized it would be better if a new encapsulation format with proper 64-bit support everywhere was created.It doesn't handle streaming?
So you can't do: tar c dirname | 7zip dirname.tar.7z ?
man 7z [slightly changed for reasonability]:
-si
Read data from StdIn (eg: tar -c directory | 7z a -si directory.tar.7z)