In the Pre-Crisis version of the character, Lana played the equivalent of Lois Lane's role in the Superboy[?] phase of Superman's career. In the stories of Superman, she moved to Metropolis to become a television journalist and a romantic rival to Lois.
In the Post-Crisis version, Lana was a childhood friend to Clark who eventually made privy to his abilities before he set out to use them for good. She made much less contact with Clark since then, but they share a close friendship.
wikipedia.org dumped 2003-03-17 with terodump