Nice, but too many parens....

% perl -le 'print join".",unpack"C4",pack"N",pop' 3232235777
192.168.1.1

% perl -le 'print unpack"N",pack"C4",split/\./,pop' 192.168.1.1       
+                      
3232235777
[download]

Update: 34 chars each... (though split\D seems to only work in 5.503 not 5.6.0)

% perl -le 'print unpack N,pack C4,split\D,pop' 192.168.1.1           
+                  
3221225472
% perl -le 'print join".",unpack C4,pack N,pop' 3232235777
192.168.1.1
[download]

-Blake