Here is another updated MS Whitepaper showing the updates from SP1 to Managed RPC/HTTPS. This was a post from Neil Hobson at http://hellomate.typepad.com/exchange/2004/06/updated_rpc_ove.html
Microsoft has released an updated paper titled Exchange Server 2003 RPC over HTTP Deployment Scenarios. This guide describes four scenarios for deploying the Windows RPC over HTTP feature in a corporate environment, for both Exchange Server 2003 Service Pack 1, and Exchange Server 2003.
Several changes have been made - see the Overview section on the link for details.