Check out the home page: http://sphinxsearch.com/

sphinx needs mysql_config program, install it with:
sudo apt-get install libmysqlclient15-dev

wget http://sphinxsearch.com/downloads/sphinx-0.9.8-rc2.tar.gz
tar xvf sphinx-0.9.8-rc2.tar.gz && rm sphinx-0.9.8-rc2.tar.gz
cd sphinx-0.9.8-rc2
./configure
make
sudo make install

WARNING: WORK IN PROGRES!!! I don't really know if sphinx works at this stage but it seems to be installed without errors