If you want to keep your source tree up-to-date with latest development you can use the CVS service provided by SourceForge.net. To check the osgNV module out with the command-line CVS client, just type the following:

cvs -z9 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/osgnv co osgNV

Once you have a fully CVS-enabled source tree you can update the source files by moving into the osgNV root directory and typing this command:

cvs -z9 update -Pd

If you can't - or simply don't want to - use the CVS system you can still keep your source files up-to-date by downloading the nightly tarball as described in the Download page.