The FWTools binary releases for Linux and Windows systems include the full set of GDAL libraries, utilities, python support and documentation along with lots of other stuff (including the OpenEV viewer). More information is available at:
The FWTools binaries for Linux should work on pretty much any modern Intel Linux system.
GDAL source releases are available in tar.gz and zip from from the GDAL primary ftp site, and http mirror site:
The NEWS file describes features added up to the most recent public release.
Late each night a development snapshot is captured from CVS and made available. These snapshots are not stable releases, and might (on a bad night) not even build. However, they do contain essentially the latest code. They can be downloaded from:
http://gdal.maptools.org/dl/daily
Refer to the build instructions for how to build GDAL from source.
The GDAL source is available by anonymous CVS from the cvs.maptools.org server:
% export CVSROOT=:pserver:cvsanon@cvs.maptools.org:/cvs/maptools/cvsroot % cvs login Password: *enter* % cvs checkout gdal
Update access to the CVS repository can be obtained by arrangement with the maintainer.