So you want to make phones rings from your website? And make some money? Well, someone will. May as well be you.
The great thing about "web 2.0" is that you can mix bits up and get something new. You just pick the best components for the job and trust to community standards to link them together. The definition of "best", however, is not so simple to figure.
Some platforms or standards will tend to dominate, or move you to conclusions that aren't quite right. And you may have prejudices that you need to get past. Much as I think Web21c is great, it maybe that another vendor is more for you. When I first read the hype about Facebook as a thriving new platform, I sort of thought it was only for kids. Then I found that half my friends were already on it.
Your job is probably to focus on what you think your customer or audience are interested in. But against that, you have to invest time in the technologies and platforms that will help you now and later. I guess Apple are a good example. They haven't dwelt on their commercial failures (remember Lisa?, or Next?) Their success is in mixing what they do well with whatever good ideas they need. The iPod was neither first player, nor following any obvious trend. And it wasn't an in house solution.
Its not as if people don't have phones already, but ubiquitous communication is coming real soon now. So find the right niche and JFDI.