Thanks to Erik Wetterberg, now there is an patched version of antenna which also supports the new Sun Java ME SDK version 3.0. See also http://eriksdiary.blogspot.com/2009/07/antenna-suport-for-java-me-sdk-30.html (http://eriksdiary.blogspot.com/2009/07/antenna-suport-for-java-me-sdk-30.html)
For simplicity, I did put the new antenna Jar-file in the SVN repository under the Build directory (I deleted the previous antenna version there).
Note: I also updated the build.xml file for the new antenna version - you need to update the Build-directory from the SVN repository in order to build with the build.xml file !
Gert