Companies who specialize in Linux, particularly Linux servers, often tout the increased reliability of the platform as a reason for choosing it over other options. Thus, when a big-name Linux vendor has their own servers compromised, it's a very interesting event. Recently, Red Hat announced that some of its servers had been compromised by outside attackers. The attack, Red Hat says, ended up resulting in several software packages being signed, which could result in downstream users becoming compromised as well if they installed the tainted software.
Red Hat has already issued a tool to detect if a system has been compromised, and claims that their RHN platform itself was not compromised, nor was any software development, such as source code for Fedora or other works.
According to Red Hat, internal security measures they had in place prevented the intrusion from causing widespread damage. It is still obviously a big red flag to many.