I ran into MS CRM 3.0 about six months ago and immediately I got addicted to it. Really simple interface for the end-users and flexible design for developers.
Microsoft really did it's best to create a really useful out of a box platform that can be used in most companies almost (and I mean it) immediately. All basic entities, attributes and relationships are prepared for the "first use".
The slogan for CRM 3.0 should be MS CRM 3.0 - Just add data.
Meanwhile I developed an application that imports data from any SQL database to CRM. I really suggest that you take a look at Michael Hohne's site (http://www.stunnware.com/crm2) and the newsgroups:
Currently I am reading a great book from MS press: Working with Microsoft Dynamics CRM 3.0. (link to Amazon).
I already went through all CRM at my own, had three day training, went deep into the database and CRM metadata, but this book still gives me new things and what is more important - very useful tips.
I took a glance at Microsoft CRM 3 For Dummies. (link to Amazon). Not disappointed, but not for developers. Nice to read if you really don't know what CRM really is.
I still owe you an explanation of the word "Afna". In my language we use it to describe the @ sign. But originally it means a person who is acting funny, usually making a fool of himself. So a play of words.