I believe that's the new relay for the ac/fan system. Some cars' ecu's would malfunction if the ac was on while you were driving. This caused engine cut-out or downright stalls at speed. I believe there was a service bulletin to fix it but I'm too lazy to search right now. Although, if i remember correctly, the service bulletin says to install it on the passenger side... ::shrug::
Holy cow Butters... that has to be it. It looks just like that... same location. Weird cause it's an N/A 2005 Elise. Maybe the orignal owner had a problem this fixed or the dealership was just proactive on service bulletins.