What is in season salt?

Many times it's MSG, so you need to check the label if you prefer to avoid it - like I do

I think it's usually sort of a secret blend and depends on the Brand. There are a lot of "copy cat" recipes out there of Lawry's and others. Here's an example : http://www.ehow.com/how_4920623_make-lawrys-seasoned-salt-home.html