The sqlmap project has moved to http://sqlmap.org.
The development is hosted on GitHub now, https://github.com/sqlmapproject/sqlmap.
You can download the latest tarball on https://github.com/sqlmapproject/sqlmap/tarball/master.
Preferably, you can download sqlmap by cloning the Git repository:
git clone https://github.com/sqlmapproject/sqlmap.git sqlmap-dev
The sqlmap files hosted on SourceForge are kept for historical reasons only and should no longer be used.