Not to lull anyone into a false sense of security... and using an admittedly small sample... I just did some test searches using Norton Site Safety, and, in the first 70 results, I'm not seeing anything like the percentages of sites identified as unsafe that the above story suggests.
In fact, on all the searches I did, for some highly competitive terms, for download sites, for pop stars, etc, where you'd expect some mischief, I only came across one site flagged as unsafe by Symantec... with a few others not rated, and two flagged as having annoyance factors. This is out of hundreds of sites, though only dozens of searches.
I should add that I do pay attention to the Site Safety warnings, even though I'm sometimes skeptical of them. (There is, eg, a social component to the Symantec warnings that might allow sabotage by competitors).
I've also encountered warnings on some sites (web/tech organizations, eg) that I'd expect to be web savvy, where I've contacted them about it, they've responded that they've looked into it, and the warnings have persisted. Hard to know what to make of that. Also, outside opinions have differed on some other sites that I've seen flagged by Symantec. I've not seen them flagged by Google.
To a degree, we do want malware warnings to err on the safe side, and at the moment I'm supposing that Symantec is doing a more thorough job on this than Google is. I would like to see some more players enter the game, though.
Again, and not to minimize the problem... Symantec is most definitely trying to sell its products, which makes me wonder about the statistics in the story just a bit.