It's going to take a while or some third party apps to take advantage of new technologies to generate speed boosts. Depending of course on what technologies we're talking about.

Snow Leopard is somewhat unfinished in a number of areas, including OpenCL. Some parts that are in fact present in the current version are also slower than older methods/paths. Hopefully this stuff will stabilize in the next 2 or 3 software updates.

At the moment however, I wouldn't recommend the update for the general public. It's more of an enthusiast item for now.

My own software needs some updates as well to jive with some of the changes Apple has made in their HID and IOKit. Not to mention providing a 64-bit native System Preference pane for systems that can take advantage of it.