Just read in Palm Treo News - something which I believe is false and alerted them to my suspicions.

"Very soon, cell phone numbers will begin being released to telemarketers. To help avoid those annoying and potentially expensive calls (yes, you will be charged for them) be sure to register your Treo smartphone number with the National Do Not Call list. Just call 888.382.1222 from your smartphone to protect your number for the next five years. Or register at their website: https://www.donotcall.gov/"

however, my favorite trusted source to check facts states otherwise.

http://www.snopes.com/politics/business/cell411.asp
which quotes USA TODAY.

In April 2005, USA Today reported that registrations for the national do-not-call list for the week ending April 2 were about double the normal level, and registrations for the following week reached a peak five times higher than average. The newspaper also reiterated [...]:

. . . the anxiety is unfounded. First, it's illegal to make sales pitches to wireless phones by using automatic dialers which is how the vast majority of telemarketing calls are placed. (One reason is that cellular users must pay for incoming calls.)

Also, most of the big wireless carriers have chosen either not to take part in the directory or to put off any plans to do so in light of consumer fears. They say any directory would include only those customers who agreed to participate and that the numbers would not be shared with telemarketers or anyone else. Congress has considered a bill to codify such rules.

in other words you would have to opt-in (not opt-out as in landlines).

anyone read otherwise.