7-8 years ago I used to develop mobile apps in both Palm OS (closed platform, just one vendor) and J2ME (open, widely adopted). Palm had the more attractive installed base back then, but as their fortunes changed, that investment is now worthless. Compare with J2ME, which kept growing thanks to support by most vendors.
Also: sure, in 8 years the iPhone may be dead and Apple bankrupt, but (1) do you really think so? and (2) do you really need to plan that far in advance?
Regarding advantages to the software developer, having just one place where you distribute, and that place being controlled by Apple, isn't a good thing at all. It may mean that it's easier to start selling, but also that you have no negotiating power if and when your app becomes a success.
The stupid music companies managed to hand over the keys to their distribution to Steve Jobs, but they're not exactly happy about the fact that he now has so much control over their fate. Apple's great at creating consumer electronics that actually appeals to people, but they don't seem to be a very nice company to deal with as a business.
So it's looking pretty good so far, even if no phones are running it just yet heh.
And the more high-brow arguments about lock-in and freedom are true, but obscure the simpler point: sorry, but I'm just not interested in paying $99 and waiting on a list for months just to run a program on my own phone!
Android has the distinct and notable advantage of actually being a working target platform for the people who want to play with it. Apple will no doubt attract a few established developers to the iPhone, but all the cool stuff will be happening on Google's platform.
In any case, both platforms are here to stay for quite some time.
Apple's user-base is attractive, but it's also putting your eggs into a basket that can be taken away from you at any time. I love Apple, but I can understand why people would be hesitant to throw money in that direction.