BizTalk 2004 SP2 can now be downloaded from -
Some of the most important fixes that are included in this service pack are:
Performance issues with different orchestration scenarios
EDI transmit fails with certain structures of outgoing messages
Disassembling large flat file messages in the pipeline stalls other processing
The rules engine is not honoring rule priorities correctly in high load
Body tracking doesn’t track the original message
Dynamic send ports causing 10 second delay in subscription
100% CPU in orchestration when calling PrepareForActivationComplete
Messages could still be delivered even though the orchestration instances were zombied
Connection problems with HTTP Request-response requests
Request to turn off FTP Throttling
Memory Leak problem in PipelineContextWrapper/Interop.ResourceTrackerbr
Apart from this a new feature of Archiving and Purging has been added that can automatically manage archiving and purging of the tracking database.
Find the list of things that go into the SP2 here.