A first release candidate of GRASS 6.4.0 is now available:
https://grass.osgeo.org/grass64/source/
-> grass-6.4.0RC1.tar.gz
To get the RC1 source code from SVN:
svn checkout https://svn.osgeo.org/grass/grass/tags/release_20081223_grass_6_4_0RC1/ grass64_rc1
An initial announcement has been drafted at
https://trac.osgeo.org/grass/wiki/Release/6.4.0RC1-News
Key fixes include improved portability for MS-Windows (native support),
hundreds of fixes, wxPython based portable graphical interface and much
new functionality.
Release candidate management at
https://grass.osgeo.org/wiki/GRASS_6.4_Feature_Plan
Please test, test, test...
Thanks to all contributors!
Markus