It isn't here yet but with the amount of information coming out of Microsoft about it lately, I suspect it will be out soon. I've put the entries important to me in bold.
SP1 - New and improved features:
Configuration Change Tracking — logs all configuration changes applied to ISA Server configuration to help you backtrack through your change history. (aka - the 'Who broke it' tracker)
Web Publishing Rule Test Button — helps you verify that the rule configuration agrees with what is set at the published web server and provides specific suggestions when they disagree.
Traffic Simulator — simulates network traffic as it would be seen by the ISA rules engine and gives you specific information about traffic processing along the way.
Diagnostic Logging Query — an extension to the Diagnostic Logging feature provided in the Supportability Pack, this feature makes it much easier to see only the data that is relevant to the current troubleshooting effort.
Support for Network Load Balancing (NLB) multicast and multicast with IGMP operations (KB 938550)
Support for certificates with multiple Subject Alternative Name (SAN) entries in published web servers (Exchange 2007 and OCS 2007 admins will enjoy this)