A common question around Zero Touch Provisioning has been, why use BizTalk Server and Human Workflow Services? 

Answer: We started ZTP in 2003, when BizTalk Server 2004 was in pre-beta and HWS was one of the premier features of the release. We made a big bet that workflow would change the way distributed applications could be designed. As it turns out, it was the right bet, but the technology from HWS was very complex and had problems with shipping some features. Once it was determined that HWS was not going to be the premier workflow platform (around BTS 2004 RC), we already had too much invested in HWS to back it out. Fast forward to April 2006, there still wasn't another workflow platform from Microsoft publicly available. So, we continued with BizTalk Server 2006 to release ZTP 3.0 by the end of summer 2006. We released ZTP 3.0 in October 2006 and .NET Framework 3.0 released in November 2006 with Windows Workflow Foundation.

Now, we're planning Provisioning 4.0 to leverage Windows Workflow Foundation. BizTalk Server will still be used for what it is best at: integration scenarios. Talking with enterprise applications (like SAP, PeopleSoft, JDE, etc) and external partners (like procurement, supply chain, etc). Also, BizTalk Server has excellent features around business monitoring (BAM). Savvy customers will want to use Provisioning 4.0 with BizTalk Server 2006 to enable near real-time request and workflow monitoring against key performance indicators (KPIs). Ironically, BizTalk provides a lot of core services that is not included with the WF framework (like a host process, pub-sub messaging, correlation, routing, health tracking) that will need to be built or leverage another WF host model (like SCSM and ILMv2). Therefore, BizTalk Server will not be required by Provisioning 4.0, but may still be leveraged.