If pkgfile is installed, add a "command not found" hook. This hook is of better quality than the one that's pre-packaged with pkgtools (it won't run when a command is part of a pipe or subshell). I should see about getting this hook accepted in pkgtools.

lib/notfound.zsh

@@ -0,0 +1,20 @@
+if [[ -x /usr/bin/pkgfile ]]; then
+  command_not_found_handler() {
+    local pkg p
+    local pid ppid pgrp session tty_nr tpgid
+
+    # double check pkgfile exists
+    [[ ! -x /usr/bin/pkgfile ]] && return 127
+
+    # do not run when within a pipe or subshell
+    [[ ! -t 1  ]] && return 127
+    read pid cmd state ppid pgrp session tty_nr tpgid rest < /proc/self/stat
+    [[ $$ -eq $tpgid ]] && return 127
+
+    pkg=$(pkgfile -b -v -- $1)
+    if [[ -z $pkg ]] && return 127
+
+    echo "The command \"$1\" can be found in the following packages:"
+    for p in $pkg; echo "  $p"
+  }
+fi