I would say Latex is used most by CS, then math, then physics, then chem. Certainly ACS (American Chemical Society) has style guides and stuff for it, and a chemistry paper I'm working on right now is in latex (granted it is a computational chemistry paper). I use it for my proof-based problem sets and I'm currently using it for a chemistry lab report. Successfully got BibTex working, modified the ACS style guide to not mark corresponding author, and added subschemes! (those were my primary accomplishments this morning, as opposed to, say, writing anything)