Just last week Morgan Stanley (financial institution) issued a report saying that:
1. "Palm's Treo phones may be at the greatest risk of all. Beyond sharing features and prices, Palm is also in the unfortunate position of having a disproportionately large number of Apple enthusiasts in its midst. Treo owners are twice as likely to own an iPod or Mac, according to a Morgan Stanley survey, and are much more likely to consider iPhones regardless of their existing Apple product ownership."
2. On top of that, Nokia's report, from last week as well, stated that "roughly 60 percent of premium phones are used for music on a regular basis". That gives Apple a huge advantage considering they have the number one player and the number one distribution system to back it up... and the number one retail channel... especially when you factor in Cingular.
3. To make matters worse (for other companies such as Palm that is), no current phone designer has the same kind of devoted fan base as Apple (unless you factor in the ferociousness of "surur" and "Malatesta" of TreoCentral fame
).
And this is to say nothing of the attractiveness and ease of use brought about with Apple's iPhone user interface.