There is an incompatibility between Gnuplot and the readline library shipping with Snow Leopard (and 10.5).
If you get these errors:
Undefined symbols:
“_rl_ding”, referenced from:
_alert in mouse.o
“_history_list”, referenced from:
_write_history_list in history.o
“_rl_complete_with_tilde_expansion”, referenced from:
_main in plot.o
ld: symbol(s) not found
collect2: ld returned 1 exit status
make[3]: *** [gnuplot] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2
Then configure like this:
./configure –with-readline=builtin
