The article is nonsense. Every privacy problem mentioned either doesn't exist or predates HTML5. Every browser has a security team that carefully reviews any new features for privacy breaches and reports problems back to the standards bodies before implementation. Everyone involved in web standards is well aware of all of these issues and tries to head them off at the pass. No website can read another website's data, none can store things without the user's permission, and nothing stops users from clearing all private data at any time.
Let's look at this systematically. First of all:
The new Web language and its additional features present more tracking opportunities because the technology uses a process in which large amounts of data can be collected and stored on the user’s hard drive while online. Because of that process, advertisers and others could, experts say, see weeks or even months of personal data. That could include a user’s location, time zone, photographs, text from blogs, shopping cart contents, e-mails and a history of the Web pages visited.
Web Storage, Web SQL Database, and IndexedDB are three of the standards commonly lumped in with HTML5, and all of them do indeed allow larger amounts of data to be stored client-side than ever before. What the article doesn't mention is it's only available to the site that stored it, and users can clear it as easily as cookies. It poses absolutely no privacy threat beyond cookies: if a server wants to store data on your computer, it can already just store it on the server and store a short identifying key as the cookie.
What the unnamed "experts" here say is therefore crazy. Nothing in HTML allows advertisers to see your location or time zone without your consent, let alone shopping cart contents or e-mail. Since the article doesn't deign to specify what HTML5 technologies are supposed to be able to do this magic, I can't refute it beyond saying it's just nonsense.
The new Web language “gives trackers one more bucket to put tracking information into,” said Hakon Wium Lie, the chief technology officer at Opera, a browser company.
Hâkon knows what he's talking about – he's a notable figure in the web standards community, editing such high-profile standards as CSS 2.1. But look at what he says carefully: trackers get "one more bucket". One more just like all the others, which can be controlled and cleared along with all the others, thus no greater privacy risk. I'd bet good money that this quote of his is taken completely out of context, and that he was dismissing the reporter's fearmongering.
Then there's mention of evercookie. But nothing that evercookie does relies on any HTML5 feature. Yes, it stores things in four different types of HTML5 storage, but again, those are cleared just like cookies. Try it yourself: create an evercookie on that page, clear your cookies from your browser's menus, and then click to rediscover cookies. You'll see that the four HTML5 methods (localData, globalData, sessionData, dbData) are all cleared too.
It's worth emphasizing, by the way, that using your browser's "private browsing mode" (whatever it's called) will completely defeat evercookie. So this is not some earth-shattering problem that no one's thought of.
The article goes on:
Each browser has different privacy settings, but not all of them have obvious settings for removing data created by the new Web language. Even the most proficient software engineers and developers acknowledge that deleting that data is tricky and may require multiple steps.
Again, this is patent nonsense. All browsers clear the new data sources whenever you clear cookies. The Web Storage spec explicitly advises this: "User agents should present the interfaces for clearing these in a way that helps users to understand this possibility and enables them to delete data in all persistent storage features simultaneously." But if you don't believe it, just try the evercookie test I suggested above and see for yourself.
There's really nothing to see here.