http://msdn.microsoft.com/en-us/library/dd441390.aspx#WorkflowScalabilityPerformance_Intro

http://henryong.com/workflow-bpm-comparison-chart.htm

http://sharepoint-geek.com/2009/12/30/enabling-workflow-with-email-enabled-lists/

http://www.spsworkflow.com/SharePoints/post/Top-10-Reasons-for-BPM-(on-SharePoint).aspx

http://blogs.technet.com/jessmeats/archive/2008/11/14/sharepoint-business-process-management-i-choose-you.aspx

http://wss3workflow.codeplex.com/

http://blog.henryong.com/2010/01/10/sharepoint-workflow-business-process-management-bpm/

http://jfattic.blogspot.com/2008/08/intro-to-sharepoint-soa.html

Can Sharepoint be molded into a SOA? IMHO, Sharepoint's web services already expose many services, and also workflows can be exposed as web services. Also, custom built workflow activities can be treated as mashup-able components (recently my company did build such a mashup/SOA  solution for a government agency)

Just a reminder, Sharepoint Designer 2007 free download read http://blogs.msdn.com/sharepoint/archive/2009/04/02/sharepoint-designer-available-as-a-free-download.aspx

Besides beeing THE Sharepoint customization tool, it can be used for non Sharepoint work, like for web pages editing.

Download it NOW !!

And dont't forget the free Sharepoint Designer templates

http://www.tqcblog.com/archive/2008/05/22/unit-testing-a-state-machine-workflow-with-delay-activities.aspx
http://blogs.blackmarble.co.uk/blogs/rfennell/archive/2009/04/03/testing-sharepoint-workflows-using-typemock-isolator.aspxù

http://blogs.msdn.com/kaevans/archive/2009/07/29/sharepoint-and-workflow-resources.aspx
http://www.tonstegeman.com/Blog/Lists/Posts/ViewPost.aspx?ID=103

Workflow for Sharepoint 2010 in Visio
http://blogs.msdn.com/visio/archive/2009/11/23/sharepoint-workflow-authoring-in-visio-premium-2010-part-1.aspx

Sembra che ultimamente ci sia molto interesse nel workflow di Sharepoint, ma gli strumenti come Visual Studio non e' che aiutino tanto a sviluppare workflow piu' complessi.

In azienda abbiamo sviluppato una metodologia e framework di sviluppo dei Workflow Sharepoint - che abbiamo spiegato diverse volte ai nostri eventi Sharepoint e al nostro corso workflow che consiste in Content Types, Custom Forms e il nostro framework che permette lo sviluppo di workflow sia sequenziali(sequential) che a stati (state machine).

Sharepoint Workflow Object Model on MSDN

http://trentacular.com/2009/01/exposing-the-state-of-a-sharepoint-workflow-instance/

http://www.thorprojects.com/blog/archive/2007/02/13/Ten-issues-and-resolutions-for-sharepoint-workflow.aspx

http://blogs.microsoft.co.il/blogs/davidbi/archive/2008/07/21/How-to-get-the-context-item-in-workflow-activity-sharepoint.aspx

http://vdcruijsen.net/post/SharePoint-Workflow-running-in-a-different-context-as-the-host-sharepoint-site.aspx

http://blogs.msdn.com/sharepointdesigner/archive/2007/09/30/getting-to-workflow-information.aspx

Q: How to change the Workflow context if e-g- Workflow is restored on another Sharepoint farm?

http://geekswithblogs.net/bloesgen/archive/2007/06/24/113418.aspx
http://blogs.msdn.com/ahamza/archive/2007/03/07/is-there-a-way-to-configure-one-send-port-to-send-a-message-to-a-document-library-based-on-a-parameter.aspx
http://blogs.technet.com/john_westworth/archive/2008/06/09/sharepoint-and-biztalk.aspx
http://weblogs.asp.net/wesleybakker/archive/2009/03/26/BizTalk-_2B00_-SharePoint_3A00_-1_2B00_1_3D00_3.aspx

How good will it be for Sharepoint?

http://weblogs.asp.net/pgielens/archive/2008/10/27/windows-workflow-4-0-is-build-from-the-ground-up.aspx
http://www.biztalkgurus.com/blogs/biztalk/archive/2008/10/30/first-look-screen-shots-of-workflow-4-0.aspx

http://reddevnews.com/news/article.aspx?editorialsid=10648

One of the innovative vendors on the Sharepoint BPM front is Italian ISV IT Consult, our excellent partner, which has been building the Josh suite since the first Tahoe/Sharepoint 2001 versions with integrated knowledge mapping and Workflow Designer based on an optimized custom BPM metodology.

Seems workflow history is only retained for 60 days http://thorprojects.com/blog/archive/2007/10/16/708.aspx
http://thorprojects.com/blog/archive/2008/03/13/750.aspx
http://www.sharepointblogs.com/llowevad/archive/2007/09/21/huge-workflow-issue-what-is-microsoft-thinking.aspx

http://www.codeplex.com/wss3workflow

Excellent blog posts about Sharepoint Workflow development

http://blogs.msdn.com/nikhil/archive/2008/01/15/sharepoint-workflow-feature-in-vs-2008.aspx

http://blogs.msdn.com/nikhil/archive/2008/01/19/sharepoint-workflow-feature-in-vs-2008-part-ii.aspx

http://reddevnews.com/news/devnews/article.aspx?editorialsid=941

http://blogs.msdn.com/sharepointdeveloperdocs/archive/2007/11/15/extending-workflow-actions-for-sharepoint-designer.aspx

http://blogs.msdn.com/sharepointdesigner/archive/2007/07/06/porting-sharepoint-designer-workflows-to-visual-studio.aspx

http://www.k2.net/bp/blackpearl.aspx

it seems better workflow tools are on the way

http://blogs.msdn.com/johnrdurant/archive/2007/06/06/milestones-sharepoint-and-atlas-falling.aspx

http://blogs.msdn.com/publicsector/archive/2007/05/07/document-workflow-in-moss-2007-enable-the-portal-to-receive-external-emails.aspx

http://blogs.msdn.com/johnwe/archive/2007/04/16/overview-of-workflows-in-moss-2007.aspx

http://blogs.microsoft.co.il/blogs/bursteg/archive/2007/03/20/10607.aspx

Sharepoint 2007 + WorkFlow

http://www.ddj.com/dept/windows/198000510?pgno=1

Jesus Rodrigues has a nice article on Sharepoint Workflow Persistence on http://weblogs.asp.net/gsusx/archive/2006/11/14/SharePoint-2007-Workflow-Persistent-Service.aspx . I'm trying to write a custom Sharepoint Workflow Designer to be used by business people/end users.

How to create custom workflow activities for use in Sharepoint Designer 2007

http://www.ideseg.com/AddCustomWorkflowActivitiesToSharePointDesignerPart1.aspx
http://www.ideseg.com/AddCustomWorkflowActivitiesToSharePointDesignerPart2.aspx

Here is another good post on Sharepoint 2007 custom workflow.

http://www.sharepointblogs.com/tbaginski/archive/2007/03/08/HOW-TO_3A00_-Create-a-custom-Windows-Workflow-Activity-and-make-it-available-in-SharePoint-Designer.aspx

Introduction to SharePoint Workflow!
http://weblogs.asp.net/jan/archive/2004/05/05/126614.aspx
http://weblog.vb-tech.com/nick/archive/2006/09/04/1753.aspx
http://blogs.officezealot.com/jkremer/archive/2006/06/25/11101.aspx
http://weblog.vb-tech.com/nick/archive/2006/07/14/1680.aspx
http://thorprojects.com/blog/archive/2006/11/26/597.aspx
http://www.topxml.com/BizTalk-Orchestration/re-23770_SharePoint-Workflow-as-Commodity.aspx
http://www.timheuer.com/blog/archive/2004/01/16/325.aspx

Decatec Sharepoint WorkFlow services (In Italian !!)