If you have installed the EDI option with BizTalk 2006 beta 2, but are not actively using it I would recommend that you disable it - just stop the BizTalk Base EDI Service in Service Manager. You may have noticed this already, but if not there is a memory leak in a covast component, displaying itself as the esp_srv.exe process slowly but surely eating up all your memory as a Task Manager screen capture shows below. Nasty little chap!
Note that this has been fixed for the next release.
Figure 1 - On this machine it had been running a week