What is an "sit" file?

I have pictures in an Olympus RAW format (.ORF I think) from an Olympus 5050 Zoom Camera. I installed the Camedia Master 4.1 software and then went to the Olympus website to download the latest update (4.2). The file downloaded and displayed in the download window. I double clicked on it but it would not open as there is no application to open it with. Does anyone know what I need to use to open this file? Is there another application that can read this file? iPhoto will not open it (I didn't think it would).

Thanks