I am looking at some seemlingly standard Haml code right now, but just noticed it starts off with a \"!=\", and 5 minutes of googling has failed to give me the answer for what
Same as using =
but doesn't sanitize the HTML
See http://haml.info/docs/yardoc/file.REFERENCE.html#unescaping_html
!= "Look <up>!"
compiles to
Look <up>!
instead of
Look <g;up>
That is used for Unescaping html
Read this HAML Documentation. It will give you all the answers you require. I just searched for HAML tags.
Do a CTRL+F for !=. != basically valuates Ruby code just like the equals would