Tomorrow, September 1, 2005, US cell phone numbers will be released to telemarketing companies and you may start to receive sales calls for which you may be charged.

To save yourself from this plague call the following US number from your cell phone: 1-888-382-1222. Your number will be blocked for 5 years. Or, you may also register online at:
http://www.donotcall.gov

***The above is a urban legend***
Added: User-contributed pointer providing more in-depth info and showing the above to be a hoax:
www.snopes.com/politics/business/cell411.asp

The truth:

"A national directory will be compiled, but numbers will be included on an opt-in basis. If a cell phone subscriber does nothing, the number will not be listed. When the directory is ready, it will be available only as part of the existing 411 directory service, accessed by calling in and asking for a specific number. It will not be published in a book or on the Internet. And it will not be sold to telemarketers.

Cell phone subscribers can list their numbers on the do-not-call registry if they choose, but there is no deadline to get on the list, as the news above may suggest."