Despite what web site polls at Gizmodo would have you believe, cell phones will not make wrist watches obsolete.
You've seen the polls. The latest one states that 2/3's of the respondents use a cell phone to tell time instead of wearing a wrist watch. First of all, it's not the most scientific survey in the world: they left off an option for people who use both their cell phones and their wrist watches to tell time. I think there is also an argument to be made that having the poll on a gadget-themed web site will get you skewed results-- much like having a survey of people leaving church will get you skewed results if you ask religious oriented questions.
Here's what the surveys don't tell you: wrist watches aren't about telling time. They are about making statements via fashion status symbols. When you go to a job interview/business meeting/cocktail party sporting an Omega or Tag Heuer on your wrist, you are sending a message to others about who you are in the economic pecking order. Yes, I know-- technical types tend to disparage this fashion statement business, but that doesn't mean it's any less real or valid. It just means that there are different modes of the same game. Look at the iPhone, for instance, which will cost you about as much as a man's luxury watch by the time you add in the data plan, etc. -- or the proliferation of personalized ring tones. It's the same game, but people play at the level they feel they can afford.
(For the record, I haven't worn a wristwatch on a regular basis for a few years now, and when my cell phone rings it sounds like Dr. Who's TARDIS.)