renan@vampire:~$ apt-cache showpkg libc6 | head
Package: libc6
Versions: 
2.4-1ubuntu12 (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_edgy_main_binary-i386_Packages) (/var/lib/dpkg/status)
 Description Language: 
                 File: /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_edgy_main_binary-i386_Packages
                  MD5: fc3001b0b90a1c8e6690b283a619d57f


Reverse Depends: 
  xserver-xgl,libc6 2.4-1