If you've been following along with the Create Your First OBA series, I've published the first two of the six parts - see below.
1. Creating the VSTO document-level solution (i.e. the custom document);
2. Deploying the VSTO document-level solution;
3. Integrating the VSTO with SharePoint content type;
4. Associating SharePoint workflow with VSTO document-level solution;
5. Customizing SharePoint (BDC);
6. Customizing SharePoint (Excel Services).
I was actually hedging on posting for the third item because I wrote an article for MSDN Magazine that covers it. So, I'll provide you with a link to the article which lives here: http://msdn.microsoft.com/en-us/magazine/cc507632.aspx.
I'm on the road again at Sapphire for the next few days, so if you're in Orlando at the conference look me up...I'll be dutifully hanging out at our booth. When I get back, I'll post on SharePoint workflow. As I mentioned in an earlier post, there's been a lot of requests for this so hang tight and I'll get to it soon.
Have a great weekend!