Although GNU/Linux users can choose a selection of PDF readers, and create PDF files in OpenOffice.org, the operating system lacks a complete implementation of the standard. With PDF about to become an ISO standard, GNU PDF
has stepped in to finalize support for this widely used format.
Google Earth client:
According to the high priority list page, "the Google Earth client is non-free specifically in order to impose Digital Restrictions Management" -- DRM, or Digit Rights Managment as it is more commonly called. Given the FSF's long opposition to DRM, as evidenced by its support of the Defective By Design Campaign and the language of the latest version of the GNU General Public License, the potential for DRM is probably more the concern here than the popularity of Google Earth itself.
is a non-profit corporation that develops free multi-media projects, best known for its Ogg Vorbis audio format and Ogg Theora video format. These formats are already well-advanced, so part of the reason they appear on the list is to encourge their use in preference to formats such as MP3 or WMV. However, work still remains to be done on such software as Icecast, a server for streaming multimedia, and Speec, an audio compression format designed specifically for speech.
Reversible Debugging for the GNU Project Debugger (GDP): GDP
is used to track what happens in a program in order to improve it. Currently, it does not support tracing what has happened in a program backwards step by step. Besides the obvious immediate usefulness in improving software in progress, this ability might be useful in reverse engineering -- a major method for helping to trace what is happening with proprietary programs so that free versions of them can be developed -- and also in developing emulators for other operating systems.
Occasionally, the high priority list changes to reflect an unexpected opportunity. For example, last December, when the Free Ryzom project attempted to raise the funds to buy a bankrupt online roleplaying game, the FSF briefly added it to the list to help raise funds. Compared to several long-standing list items, an online game wasn't essential to free software, but the FSF hoped that the popularity of gaming would attract more users and -- since games often drive hardware advances -- encourage video card manufacturers to give more support to GNU/Linux. However, the effort failed, and the list returned to more immediate considerations.
Continued: The list is both encouraging and discouraging