Add the following debian source provider to /etc/apt/sources.list
deb-src http://cran.r-project.org/bin/linux/debian squeeze-cran/
Download the KEY from Johannes Ranke (CRAN Debian archive) jranke@uni-bremen.de to be able to use SECURE APT
gpg --keyserver subkeys.pgp.net --recv-key 381BA480
gpg -a --export 381BA480 > jranke_cran.asc
apt-key add jranke_cran.asc
Then update the list of available packages, and install R2.14.1
apt-get update
apt-get upgrade