I like to stay on top of developments in the micropayment world since DC is a member of this small community. I'm skeptical about the details of this specific system on Steam actually resulting in a micropayment system that people use.
However, I think you can see how micropayments are going to eventually catch on -- and that's when people are, as a side effect of some other motivation, already part of a large network of users whose financial information is already in place so that they can pay without risk or inconvenience.
As I wrote about here (https://www.donationcoder.com/Articles/One/index.html), the term "micropayment" is probably going to turn out to be a misnomer. The key issue for developers who wish to survive on trivial end-user payments is not the size of these payments but the ease in which they need to be doable before they will become financially viable to a producer. For this to happen, we need a kind of financial account facebook/myspace/twitter thing, where most of the planet is signed up. I don't know how long it will take to get to that point but I think it's coming.
Valve's Steam software has a new feature for game publishers that lets them sell additional downloadable content, or DLC, from within their games. Valve says the new system will allow users to purchase and add additional content, even on titles that were not purchased through Steam's game store, just like it does with physical software titles that were purchased from other retailers.
http://news.cnet.com/8301-17939_109-10198392-2.html
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