Seattle recently enacted a couple of ordinances which will make it easier to opt out of yellow page phone book deliveries. These ordinances provide for stiff penalties for companies delivering unwanted directories to your home if you have opted out. Seattle has contracted with Catalog Choice, an outside agency for this service. Catalog Choice handles junk mail as well. They do require creating an account to manage which phone books (if any) you wish to receive. More information is available at Seattle Public Utilities. SPU maintains a Frequently Asked Question page as well with the answers to a lot of potential concerns.
You have to take the initiative to opt out of the delivery. Many folk already just drop their phone books in the recycle bin the day they are received. Opting out solves not only the immediate problem of unwanted yellow pages, but also the overloading of the recycling operation, and reduces the waste of forest resources. Your opt-out selections must be made 30 days in advance of the scheduled delivery for them to be honored. The Dex deadline for opt-out is May 16th.
The web site for Catalog Choice is slow today (May 5th) due to the extremely high percentage of Seattle residents who wish to opt out or otherwise manage their yellow pages deliveries. The ordinances are not popular with the phone book companies, and some are mounting a First Amendment challenge to them as noted in this article on the PI. Update: As of May 10th, 105,000 Seattle households have opted out per this article.