Here's a great article on the new 3G Phones in Japan.
It talks about how it's been more successful than planned so far, what the competitors plans are, etc. For example J−Phone's 3G system is supposed to support the world standard which supposedly means you could use the phone in over 100 coutries implying that NTTs do not.
One thing that stuck out to me as cool, NTT got smart and made it so you can use multiple phones on the same *line*. What does that mean? It means you can buy multiple phones and choose, based on your fashion, which phone you want to take with you. The pearl white phone that matches your bag, the pink phone with hearts that matches your summer skirt, the Ferrari model to match your lipstick, the leopard skin model when you're going to hang in Shibua.
Of course I'm sure people outside Japan will think it's silly but here in Japan, cell phones ARE fashion which is one reason why people upgrade sometimes more than once a year. Like wearing the same shoes everyday or the same watch everyday, many people here get tired of the same phone day after day and want a new phone.
I suppose you can do this in the states with the systems that use the ID cards like Pac Bell did. The difference in the states is that the cell phone companies have not tried to market phones as fashion which is arguably their mistake. But, it's clear people are interested in it even in the states as evidenced by all the stores that sell new cases for your phone.