Fill Flash strength (350D)?
My 5D has ISO 50 and it is great for shooting outdoors at large apertures. My understanding is that sensors have a native sensitivity that is translated into ISO. I suspect that the native sensitivity of a P&S camera is lower than that for a dSLR. To get lower ISO's the signal has to be attenuated. But to answer your question, you can get low ISO's if the camera manufacturers want to provide it.