I got to borrow both of these from work.
The value is in the S30. The only 3mp with manuel features, no the nikon 885 does NOT have them.
Also the difference is only .8mp. 3.2 and 4.0.
the s30 can go up to ISO 800
the s40 can only go to ISO 400 because 4,000,000 pixels in the same space as 3,200,000, the 4mp will be grainier, noisier.
the s30 is also faster, not because of faster ram, but smaller file size. but remember, you really only need 1 or 2 for a great 4x6 if you have a pro lab print it.
if you use the S40 and change the res to a 2mp, you are still useing smaller sensors on the CCD, so the S30 will win again.
People don't buy higher megapixel cameras for the higher res, they buy them for the features, now that the s30 has them, there really isn't a need for the s40.