Diane Lane is an actress who has seemed perpetually 37 for about 20 years. There's a weary, sexy worldly wisdom to her that has allowed her to appeal to both men and women, either in erotic "thrillers" like "Unfaithful" or big crowd-pleasers like "Secretariat." Thirty-seven is a good age for an actress to seem; old enough to be respected, but young enough to still be attractive to all age groups. Yet the 46-year-old, onetime Oscar-nominee Lane will play Martha Kent , Superman's "mom," in the upcoming Superman reboot. She has played moms before, of course, but not mothers that have typically been portrayed as matronly rocking-chair dwellers. To be fair, with Annette O'Toole on "Smallville," Superman's adoptive parents have gotten younger in recent years; it's still rumored that Kevin Costner will play Pa Kent, after all. (Actually, that's totally not fair: Costner is 56, almost a decade older than Lane.) Lan