Brief information: These days GRASS GIS 7.0.0 has been released!
This major release took more than six years for the GRASS team to develop. They have done great work and built in more than 10,500 fixes and improvements. Version 7.0.0 will also enjoy long-term support.
Now there is a considerable increasement in performance in many processing modules of the software. In some parts it is even more than a thousand times faster than the old version!
A bunch of new modules have been added. Until now I had no time to test some of them, but they really sound promising.
Written enough! Give GRASS GIS 7.0.0 a try!

For further details, visit: http://grass.osgeo.org/news/42/15/GRASS-GIS-7-0-0/