"Added to HTML5" is misleading. More specifically, the bitcoin scheme was added as a valid scheme that websites may register themselves as handlers for via navigator.registerProtocolHandler, a list that already includes mms: xmpp: webcal: tel: and other misc schemes. It doesn't specify any kind of support for the scheme for the browser.
No. Evernote, dropbox and flickr are all services implemented by a single organization each. You could just to use HTTP to link to a flickr profile. Bitcoin is decentralized. It is like a protocol. Each user can have his wallet stored in a different service, or even in his computer.
The spec allows a wallet service or an application to add itself as a handler for bitcoin: links. Similar to mailto:, the user can choose the application which can listen to those links. It could be gmail, or thunderbird, or outlook.
Its like a protocol but if it was a protocol it could be used by different currencies. Just because it is distributed does not mean it cannot have a URI to identify some metadata about the currency being used.
My point is.. you can have any application or service to handle bitcoin address clicks. You can choose to open your wallet service on any website, or an application which manages your bitcoins stored in your hard disk. It isn't a HTTP link, and there isn't some central web service to transfer bitcoins.
Both paypal and googlecheckout are implemented in one way. It is not a protocol. Only the service's website can handle the request for payment in those currencies. Bitcoin is decentralized. The user can install/associate any service/application to send bitcoins, much like emails using mailto:
Basically, the WHATWG and W3C specs have diverged and there is no clear plan for them to meet up again. So, just because WHATWTG has added bitcoin links to their HTML5 spec does not mean that W3C will add bitcoin links to theirs. W3C is generally considered the more respected/"official" spec out of the two. (I would not be surprised if most people who've heard of the W3C have not heard of WHATWG.) I know that browser developers care about being W3C-compliant. I'm not sure whether they care about being WHATWG-compliant.
Browser developers care about being “WhatWG compliant”, because the WhatWG HTML group is composed by browser editors, they work with the W3C HTML5 group, and the HTML5 specification is based on the WhatWG’s HTML document.
I was speaking for myself rather than making a principled stand; my site still links back to some documents on my old university's system, via gopher. Perhaps there is an http equivalent that new students would use, but if there is then I don't have access to it.
It is referring to the registerProtocolHandler function. The function allows you to register handlers for custom schemes, so that you can do clever things with links like <a href="awesome://example.com">awesome</a>.
The "web+something" namespace is what we should be using for our custom scheme handlers, but there are a bunch of other web-related schemes that will be fine to use too... "bitcoin" is one of the OK ones.
It's not a big deal as far as I can see... basically any scheme that is popular enough or documented enough and isn't supposed to launch some external application could probably get white-listed if you asked nicely.
Paypal payment is implemented only using paypal website. It is pointless to add it because no website/app can register as a handler for that URL scheme to implement it in any different way.
Bitcoin payment is not centralized and processed by one agency.