Mr Dave has written an interesting blog in plug-in development, which is the replacement for the callout-techniques used in CRM 3. There are a lot of architectural differences between callous and plug-ins. If you are planning to use plugs, dig in:

I hope to be writing some postings of my own concerning CRM 4.0 soon, but I still havn’t got my hands on a version 🙁

Gustaf Westerlund
CRM and SharePoint Consultant

Humandata AB