What were Sayid and Locke talking about to Kate when they said The light shinning on Echo's walking stick was going to show them the way????

I think they are just referring to the fact that the light was what caused Locke to take a second glance at the stick during Eko's funeral (I still recall the light coming down through the trees in that scene as being particularly gorgeous), which is what led Locke to read the words "Lift up your eyes and look North" on the stick. Still it does seem a little bit outlandish, Sayid speaking in such a "poetic" way. Or is that disquieting? :D

I had totally forgotten that -
They did have an idea of where to go-
So why did Sayid sound poet when telling Kate

i thought Sayid sounded more sarcastic...

Definite sarcasm.