Apple has recently begun surveying longer-term iPhone users. Much of the survey focuses on post-purchase satisfaction with the iPhone, as well as with satisfaction over the iPhone 2.1 software update.
One page of the survey, however, is devoted to "Feature Requests," both in hardware and software. The survey requests customers to select the top 5 features they'd like, and to rank them from 1 - 5.
Looking at the list, it would be hard to pick just five, personally. They have items such landscape mode in email (which has recently been addressed by a number of apps in the App Store), other carriers, cut-and-paste, Flash/JAVA, a user-replaceable battery (the word replaceable makes me wonder if they mean swappable batteries, as most phones have, or just a kit to replace a battery in a difficult, but still doable way), and other others.
If their asking about these features now, it's would seem to point to the probability that they haven't implemented any of the above features yet. So I wouldn't expect to see any of them soon, but hopefully, some day.