From the Edenwaith link:
As of February 2009, Edenwaith will no longer actively develop Untar. In our efforts to focus on current and future projects, Untar has been discontinued. We recommend that users switch to Untar's sister application GUI Tar, which provides all of Untar's capabilities with the addition of being able to compress and archive files. Since Untar is released under the GNU Public License, its source code will still be freely available for others to use.