Sony has clarified that the only Satin Silver we will be seeing on the 40GB PS3 is the front detail, instead of the shiny chrome finish that it has on the 60GB version. Official word is quoted below:
"Both 40 and 60GB models are in shiny black, but the 60 has a shiny, chrome like strip and detailing whilst the 40 uses a satin silver detailing. If you look at the pictures on the Press Centre you can see the subtle differences."