Support for display of GB18030 glyphs has been added to Java for the zh locale. The 1.1.8 JRE in use by Notes/Domino does not itself support GB18030 natively, but if you have the GB18030 OS support installed on Windows 2000 or Windows XP (i.e., the Simsun-18030.ttc font), and your Java agents and applets use GB18030 Unicode glyphs, you will see the proper symbols.
We've also provided the older font.properties.zh file for use if you don't have the OS-level GB18030 font support installed. In some very rare circumstances involving server agents that have GUI's or use of the JRE in Notes/Domino by an external app, you may see messages like "Font xxx specified in font.properties was not found". These messages are benign and can be safely ignored, but if you want to get rid of them, just replace the [notesbin]\jvm\lib\font.properties.zh file with one named font.properties.zh.non_gb18030.