One thing I should mention amongst all the posts about whether the ScanSnap is compatible with Snow Leopard. Back on August 26, NeatWorks for Mac version 2.1.7 was released that makes the software compatible with Snow Leopard.
From their blog post on the topic:
The next major release of NeatWorks, slated for the fall of 2009, will deliver new features that utilize technologies such as Quick Look, Core Image, and Image Capture that Apple introduced in OS X 10.5 and improved in OS X 10.6.
Sounds good! NeatWorks users, make sure you upgrade if you are going to take a look at Snow Leopard.
(Source: Neat Company Blog)