CFCs and thread safety

Lots of chatting going on about CFCs, application scope,?and thread safety on the CFDev list.? Popular topic that rears its head often.? What to do?? Have to var scope your variables used within cffunction definitions in your CFCs.? This means all variables!? Or does it?? So, make sure you var scope those iterators and query names.? But what about CFFILE or CFFTP?? So far the verdict is this:? some variable scopes are fixed in CF and live in the request scope, therefore no worries, safe as is.? Now, is this the correct way to say this?? hmmm….