I haven't played with this too much, but does Mist need a local copy of the entire blockchain? If so, I'm not sure these decentralized applications will be accessible to the average user. On the other hand, the application in the tutorial directly deals with Ether so the user may already have a fully validating node. Are decentralized apps created on Ethereum intended to always involve Ether? I suppose Ether is used to reward the miners for hosting the application?
For now Mist requires a full blockchain but we already started testing a light-client on the node that would avoid that.
Not all app need to show ether to the user, but that is the currency used to pay miners for transaction fees. There are ways in which the app developer can try to abstract the concept of ether using other currency, or even subsidising the users by paying their cost via other means (like what digix gold does).
Ether is not used as a reward for hosting the app, but for changing saving data and changing states on the blockchain. We will have a P2P solution where users are paid to host actual application files.
The key difference though is the decentralization part. The backend cluster can have downtime or be shutdown, with Ethereum it wouldn't have downtime ever and can't be shutdown either.
It is 'pay-to-play', but the cost is often minimal (half a cent per transaction), nothing is really free either, when one uses something like facebook one is paying indirectly one way or another (though personal information, seeing ads, etc..)
Do you really think putting a micro payment system on any sort of interaction is some sort of success? Obviously, I think a forced micro payment is a horrible idea.
It is migrating away from a free web to something that is purchased on every page. And given that bandwidth and storage are getting cheaper and cheaper, that system is a travesty.
And not to mention, when big mistakes like what the DAO did, mommy and daddy (Ethereum) will make it all good.
Actually cheaper bandwidth and storage only make these type of systems more accessible and the micro transactions cost even more negligible. It is migrating from an illusory free web to a truly free one in both senses of the word.
Not all applications running in these sort of platforms need to be about money either, and "mistakes" like the one in the dao happen can happen in all software, it can be coded as centralized or as decentralized in terms of management as you wish, the key difference though is that the platform itself is decentralized.
Additionally, in the Serenity phase of Ethereum contracts will be able to pay for transactions, which effectively makes transactions free if you like that sort of model, is that something that would make you happier torwards Ethereum and other decentralized systems?
I posted it as "How to build server-less applications for Ethereum" because I assume most people don't know what Mist is. But someone changed it back to Mist.
