The Chinese used cell phones all the time, and several people in our delegation used cell phones and Blackberries regularly. I was not so successful.
The Blackberry service that I subscribe to is limited to the continental U.S. My Blackberry worked in China only after my assistant back home called Verizon to do something to change my service, and even then it sounded expensive (I haven't seen a bill yet). It sounded like it would have been better to have called Verizon to change my service before going to China, instead of after I got there. I used my Blackberry only occasionally for phone service, and never for e-mails.
I was never aware of any blackout areas. On the day that we visited the Great Wall, I used my Blackberry successfully from the bus while traveling in the mountains (try that in Vermont!) and from the Great Wall itself.
My suggestion is that if you are going to China, check with your service provider before going.
