Debian Lenny EOL in two months. Security support for Debian GNU/Linux 5.0 (code name “lenny”) will end 2/6/2012.  If you are still using Lenny, you should run a distribution update to Squeeze in the next 60 days.

The Debian project released Debian GNU/Linux 6.0 alias “squeeze” on the 6th of February 2011. Users and distributors have been given a one-year timeframe to upgrade their old installations to the current stable release. Hence, the security support for the old release of 5.0 is going to end on the 6th of February 2012 as previously announced.

Source: http://lists.debian.org/debian-security-announce/2011/msg00238.html