Just to tell you that we just added into the OpenOffice.org tinderbox build an x86_64 slave. Moreover, it builds with gcc-4.1.2 and with FSF java. So, if your build breaks in java files, check whether you did not write in an "übersetz mich" or other umlaut containing words. The other typical errors might be extra qualifications in declarations of C++ classes and/or treating of ULONG/LONG as if they were assured to be 32-bits. Keeping this in mind might prevent too frequent red status.
Thanks to Intel that provided this machine last year. And thanks to Christian Lohmaier who is guiding it and forcing it to do the right thing.