The "micro billing" proposed in this article is composed of micropayment that are tallied in the background. As far as I can tell, the only difference between microbilling and micropayments is that there's no confirmation dialog.
You're still deciding every day whether or not to spend the 20 cents.
I disagree. My interpretation of Shirky's thinking is that the dialog is the issue, rather than the payment size.
The key is to create an almost friction-free and fair method of payment. People are happy to pay a fair amount for content (cf. the piracy argument) as long as it's hassle free.
The usage component is essential so that people don't end up paying for services they don't use. If you stop using a service you stop paying for it. No lock-in.
You're still deciding every day whether or not to spend the 20 cents.