If you read this blog often, you'll know that I have a book that just became available: Pro SharePoint Solution Development published by Apress. They have made Chapter 1 available on their web site: http://www.apress.com/book/supplementDownload.html?bID=10267&sID=4275 and here is a link to the source code for the book: http://www.apress.com/book/supplementDownload.html?bID=10267&sID=4242.
I'm also working with MSDN who should be posting the Excel Services based solution in Chapter 6 on their site in June.
I'll send you some updates from TechEd. You can watch my first session (200 level workflow) live through live meeting and TechNet. The session is on Tues June 5th at 11:45am Pacific Time. http://www.virtualteched.com/Pages/OnlineSessions/OnlineWebcastsOffice.aspx