Wi-Fi cellphones
According to this WSJ story (subscription required), the cellphone companies may be in for a bumpy ride soon:
Last month, Japan's largest cellular carrier, NTT DoCoMo, started selling a cellphone that looks like any other. Most of the time, the phone, made by NEC, works like any other, too: When its owner is out and about, it uses standard cellular technology to transmit calls.
...Why does any of this matter? Each minute of wireless calling over Wi-Fi is a minute of calling not made over a cellular network. That has the potential to shake up the world of cellular calling.
Unlike a traditional cellphone call, which comes out of your bucket of paid minutes, calls over the Internet may not be counted at all. That means that if you were in your office -- or eventually your home, or Starbucks or any place that has a Wi-Fi connection -- you could make unlimited free calls (not counting the cost of the Internet service). That is particularly significant because roughly a third of all cellular calls actually are made from an office or home, according to a Yankee Group survey. DoCoMo's phone will work only if it is configured with a specific corporate Wi-Fi network; you can't just use it at Starbucks.