[..]
No, I don't think they are since it's the same in the fifth edition of the book. I think the explanation is that Lammle is going to use that particular lab configuration over and over again in the book, so he wants you to set it up correctly since the beginning.
Those port connections are trunk lines between the switches. They are used to exchange vlan information. They are not used in the example you cited but Lammle is going to use them in the last lab before the summary in chapter 8 entitled "Configuring Switching in Our Sample Internetwork".
Bye,