Just because no one is talking about it doesn't make it less relevant. Globally Symbian IS dominant, and Apple has only made small in-roads in overall market terms.
Clearly it's not because Symbian is a solid OS. S60 is a usability abortion and UIQ is basically DOA. The Japanese mutant versions are hardly any better. Hell S60 basically failed at launching a touch-screen version.
What they do have is a boat-load of devices. Nokia alone covers basically every segment imaginable from the very high end to the very low. They've taken a shotgun approach that very directly targets individual consumer preferences.
Android is headed down the same road, except with a MUCH more polished product. Is it as good as the iPhone? I don't think so. Is it 'close enough'... I think it is, and it's only going to get better. With something like 18 phones coming out and widespread carrier pentration, I think this is a done deal. Android, in the United States in particular, is going to assume a dominant market share position.
What does that mean for developers? I have no idea. The jury is still out as to what the demographic make-up of those users will come to look like. Will they buy apps? Will they support a app-store style eco-system? Will they use the web features and consume data like iPhone users? I have no idea, and really can't come up with anything resembling a sensible guess.
I think Apple believes they have the premium user cornered. I think they're betting that the types of users drawn to Android phones won't provide very much market value. That is why they've stuck to this position.
The whole thing is very Mac/PC all over again. I wish I knew how it was going to play out in the end.