I have also seen people using their cell phones like they were on land and it didn't matter. Just crazy - it can cost as much as $5 minute when you add thr ships charges and your carriers roaming charges.
I love that texting story.
Yes - some phones like iPhone have a feature called "push" where they stay on and keep downloading content from pages like CNBC which offers real-time stock quotes. You have to be careful they are not logging into the network to do that - an iPhone should be put in "data off" while on a cruise ship. That way you can get a phone call in an emergency, but no email.
O have used a verizon blackberry on a cruise and the bill was not nearly as high as my iphone. One email from Mexico cost me about $12 as I recall. On a Blackberry that would cover an entire day. That was MY personal experience, though. I can't say that is always true.
Actually - if you have an iPhone (from AT&T) you can use this chart to see how much a cruise ship phone call will cost you:
Wireless International Rates - Wireless from AT&T