$ apt-cache showpkg gzip
Package: gzip
Versions:
1.3.5-12
(/var/lib/apt/lists/gb.archive.ubuntu.com_ubuntu_dists_dapper_main_binary-i386_Packages)
(/var/lib/dpkg/status)

Reverse Depends:
  ubuntu-minimal,gzip
  file-roller,gzip 1.3.2
  rsyncrypto,gzip 1.3.5-4
  magicfilter,gzip 1.2.4-33
  krusader,gzip
  hdup,gzip
  education-standalone,gzip
  battery-stats,gzip 1.3.2
  backup-manager,gzip 1.3
  apt-file,gzip 1.2.4
  ubuntu-minimal,gzip
  file-roller,gzip 1.3.2
Dependencies:
1.3.5-12 - debianutils (2 1.6) libc6 (2 2.3.4-1) less (0 (null))
Provides:
1.3.5-12 -
Reverse Provides: