Aside from a few improvements, and some direct hardware support, the new release for Serato isn’t anything major. Here’s a snippet from the ScratchLive site:

Thursday 22nd May 2008. Auckland New Zealand.

Serato Audio Research is pleased to announce the release of Scratch LIVE 1.8.1.
This is primarily a maintenance release to improve performance and stability and also introduces support for the following 3rd party controllers:

Denon HC-4500
Denon HD-2500
Numark DMC2

Scratch LIVE 1.8.1 includes changes and improvements to the following areas:

USB performance
iTunes Library support
External Midi control
Offline Player
Deck and playback controls
Library Crates and Tracklist
Preferences and setup options
Video-SL integration

Go here to see the full list of changes.