I added my home phone to the do not call list and it works GREAT. Now the only sales calls I get are from my phone provider, offering me more services (a little ironic). But they don't call very often, we used to get numerous telemarketer calls EVERY DAY.

I hadn't heard anything about Cell Phone s being added, I just got this from the website:

Q: Can I register my Cell Phone on the National Do Not Call Registry?

A: Yes, you may place your personal Cell Phone number on the National Do Not Call Registry. The registry has accepted cell phone numbers since it opened for registrations in June 2003. There is no deadline to register a home or cell phone number on the Registry.

You may have received an email telling you that your cell phone is about to be assaulted by telemarketing calls as a result of a new cell phone number database; however, that is not the case. FCC regulations prohibit telemarketers from using automated dialers to call cell phone numbers. Automated dialers are standard in the industry, so most telemarketers don’t call consumers on their cell phones without their consent.

I would like to say that my home phone is on the do not call list, and it really does work. We got numerous calls everyday, it was very annoying! Now we do not get any calls except occasionally we get "offers" from our telephone service (Do you want to upgrade? do you want this package? etc).
So I would recommend people to enlist. It just seems that the alert involving Cell Phone s is incorrect.

This is not entirely true:
http://www.truthorfiction.com/rumors/c/celldirectory.htm