Transferring a domain registration generally requires a minimum one year renewal. This is true with DreamHost or another registrar. Despite the wording, my understanding is that it is technically not a transfer charge (as what you are paying for is extending the registration one year), but it may seem like one. The only exception to this would be if you have not yet used the one free domain registration that is available under each hosting plan.
There is no charge for transferring domain hosting, assuming you still have "room" for hosting another domain under your current plan.
The kbase info you refer to is under transfering domain hosting. The information for transferring domain registration is here.