|Quoting BHMBAGLOCK (Reply 2):
They bought a company that's had the name for a number of years.
Doesn't matter. The name has to be in use, and has to be "famous." Unlike a patent or a copyright, you don't get to hold onto your rights in a trademark unless you actively use the trademark. That applies to registered trademarks too.
Even then, if the Apple iPhone is a different market from the Cisco iPhone, they both may legally be called iPhone. (Note I said *may*. I would need more information to be sure.)
EDIT: just did a little research (didn't take much) and Apple may have a much bigger problem. The Cisco product is actually called "Linksys iPhone" and is on sale. You can even buy it on Amazon, and of course, it looks like a small mobile phone - just like the Apple iPhone is.
So, in this case, for Apple to win, it's going to have to show that "iPhone" is a generic term. You can't keep a registration of a generic term as your trademark. And if you own a trademark and it becomes generic, say goodbye to your trademark. (Just ask Thermos, Escalator, and Band-Aid.)
If I recall correctly, Apple got burned by this very thing some time back with their own trademark. I think they tried to trademark everything with "i" in front of it - iPod, iMac, iBook, and a few others. Mark my words, they'll lose their iPod trademark in about 5 years.
[Edited 2007-01-12 16:08:54]