Thanks dougkinzinger for the heads up in BPN
Microsoft have silently updated their Mouse and Keyboard software to version 5.0 today. Including in the upgrade is support for the latest Keyboard and Mice combos and the new "tilt" mice.
If you're used to assigning buttons per application then this release isn't for you, Microsoft have strangely removed this functionality from this updated software.
View: View Information
Download: Download IntelliType 5.0
Download: Download IntelliPoint 5.0
News source: Neowin's BPN