The Windows Server 2003 Service Pack 1 Release Candidate is available for download at http://www.microsoft.com/windowsserver2003/downloads/servicepacks/sp1/default.mspx
The MSDTC changes are similar to the ones described at http://blogs.msdn.com/florinlazar/archive/2004/06/18/159127.aspx
In addition we have a new interface called IDtcNetworkAccessConfig2 that allows the management of the new configuration settings: inbound/outbound network access and the authentication level.
If you have questions or feedback about this Service Pack, you can post at the dedicated newsgroup: http://www.microsoft.com/technet/prodtechnol/windowsserver2003/servicepack/newsgroup.mspx
Please try it out, we appreciate any feedback. Thanks!