http://forgottenrealms.wikia.com/wiki/Lantan has a list of sources, but none are expansive. Races of Faerun (3E) has some info on the Lantanna people. You could also look up info on Gond in Faiths and Avatars (2E), Grand History of the Realms
Thanks a lot guys! Looks like that's about all there is concerning Lantan unless Ed has some personal notes hidden away somewhere. I did find an interesting tidbit about clockwork animals and dolls form Lantan in Aurora's Whole Realms Catalogue. Did you know that clockwork fighting dolls that were made in Lantan staged a mutiny in Baldur's Gate once?