That sounds like Rhapsody/Mac OS X Server (which would have been Platinum). And it is, indeed, quite snappy. I have it on a Wallstreet G3 and it runs very well.
mrkpdl
The aqua interface first shipped in Mac OS X Developer Preview 3. So they could be referring to DP2 which had a platinum like interface but was released after Apple had moved on from the rhapsody concept.