Yea the iPhone 4S does have 512MB ram:
AnandTech - iFixit iPhone 4S Teardown Confirms 512MB LPDDR2, MDM6610
Its not so much about needing it to be smoother, better. Its about taking advantage of what the extra ram offers. I'm sure there is some benefit of the extra ram that the iPhone 4S is missing out on, even if its better multi tasking.
And I'm curious as to how its faster than the iPhone 4S too. Most of us that followed benchmarks already knew the 4S was gonna be a beast when we saw iPad 2 benchmarks.