Yes. It saves the RAW + Jpeg, and after the RAW is saved, it shows the preview (or more like review).
Please keep in mind that saving RAW can - depending on the speed of the card, and the sensors resolution - slow down the saving process considerably. For example: My SX100 needs approximately 1.5 seconds to save a RAW image (9MB in size) on a "SanDisk Extreme III" card. On a standard el-cheapo-card it took around 3 seconds.
I assume 'larger' cameras with better hardware, such as the S5 or G7, may be faster at writing to SD cards. At least i saw in the wiki that those - and a few other - cams can write with speeds of up to 19 mb\s.
So basically, what you want is possible, but i just want to warn you, that you *may* not be fully satisfied with the results..
Regards