As you may have already heard, Cisco sued Apple for trademark infringement over the iPhone name. (See the CNet story. See the Cisco press release and the Cisco blog post from their general counsel.)
A basic trademark rule: if the goods or services sold under a mark would overlap with an existing mark, then the first person to use the mark wins. (Unless you get into intent to use applications, which would muddy things a bit, but since that doesn’t apply here, we can forget about it for now.) Cisco (via assignment from acquiring InfoGear) has priority to use the iPhone mark in connection with “computer hardware and software for providing integrated telephone communication with computerized global information networks” and a first use date of June 6, 1997. (See the trademark registration information from the U.S. Patent and Trademark Office.)
Could Apple and Cisco come to an agreement where the both could use the name iPhone? Yes, they could have agreed to whatever they wanted.
Wouldn’t more people associate Apple with the name iPhone, rather than Cisco? Perhaps, based on the existence of the iMac, iPod, and iTunes. But that’s not the point. The point is that the iPhone trademark was first used (June 6, 1997) before the first iMac was introduced (May 6, 1998; see this EveryMac page for details).
What’s in the lawsuit? (See a PDF of the complaint.) A few interesting things. For example, Apple approached Cisco to acquire the mark in 2001 (see paragraph 17). There is a contention that Apple was using a shell corporation called Ocean Telecom Services LLC to attempt to register the name iPhone in other countries. The complaint points to an Australian trademark application by Apple and a U.S. trademark application by Ocean Telecom that claim priority back to the same trademark application in Trinidad & Tobago (see paragraphs 18-24). Even if this allegation is true, it really doesn’t make much sense from a trademark perspective since the application would be likely to be blocked by Cisco’s iPhone registration. The rest of the stuff (the claims and relief sought) are standard trademark infringement stuff that you would find in virtually all trademark infringement suits.
What will be the outcome of this? Sorry, try your question again later. Trying to predict stuff like this is a bit crazy, since we can’t really know the full dynamics behind the negotiations that led up to this. But a good guess would be that Apple changes the name of the product. Maybe similar to the Apple TV device, i.e., Apple Logo Phone.