I used to have a Blackberry as part of my out-of-the-office arsenal. Now, I have to admit that mine must almost qualify as a collector's item - it's a model 957, one of the earliest built. No built-in phone or internet access, but it did allow me to access email. I travelled with it everywhere and because of it, was able to stay on top of my email.
Now to the myth buster part - one evening we took off from Chicago O'Hare and we had the usual pre-takeoff announcements with all the dire warnings how electronic devices would interfere with navigation equipment .... I must have been engrossed in something else, because I neglected to turn off my Blackberry. As we were cruising at about 10,000 feet above Chicago, my Blackberry suddenly started vibrating (I had turned off the audible notification). I had an immediate impulse to turn it off before something disastrous occurred which the NTSB investigation would link back to my Blackberry. However, as nothing immediate happened, curiosity got the better of me and I checked the incoming email. Not only did I read it, but I also successfully responded - and lo and behold, we continued on our way and reached our destination as scheduled.
I was left wondering about the real reason behind the pre-takeoff warnings. Perhaps the airlines wished us to use their outrageously-priced services instead ?
Here's a photo of my Blackberry - yes it still works (sort of) although it hasn't been hooked up to an email server for years.