Poor Spencer Harbar,  he has produced some very good, detailed and useful  articles on applying Kerberos and then TechNet publish an article “Using Kerberos for SharePoint Authentication”  full of the very points that may work in the lab but not necessarily in the real world.   I sense he was a bit miffed on writing this article!

He has listed the main points to be aware of in this article on his blog post:

TechNet Misinformation: How NOT to use Kerberos for SharePoint Authentication

You will be able to find other Kerberos related articles in his blog.