A new whitepaper Understanding Design-Time Properties for Custom Pipeline Components in BizTalk Server is available here. From the blurb:
This article explores the details of designing and building Microsoft® BizTalk® Server 2004 and BizTalk Server 2006 custom pipeline components that use design-time properties. Full source code for a sample custom pipeline with design-time properties is included.
I will be assembling a Pipeline resource page in the next few days. In the meantime, take a look at this new whitepaper if you have feedback, send it in.