Great thread, but responses to the OP are really very dependent upon rules & regs governing scope of licensure in each state.
Here in TX, EMT practice is limited to 'first responder' environment -- not in a hospital. If they work within a hospital, it is only as a tech supervised by MD or RN. Under NO CIRCUMSTANCES would an EMT allowed to triage patients in a TX ED - patient assessment cannot be delegated by an RN to an "unlicensed person" (which is what the EMT would be considered if functioning outside his/her scope of licensure). It is a violation of the Tx nurse practice act.