Here is an interesting post on Richard Seroter's blog on persistence points.
If you plan to have a business process integration that could be interrupted and resumed due to external factors, then knowing about persistance points is very useful and important for the correct functioning of your BizTalk application.
Check it out here…
http://seroter.wordpress.com/2007/01/02/orchestration-handling-of-suspended-messages/
Regards
Benny Mathew
Seamless Integration Solutions
BizTalk Consulting, Development, Training
http://www.seamless.in