Danny Sullivan has put onto paper what many of us had been thinking already. These days, when you diversify your traffic sources, you tend to think Google first, and Digg/Stumbleupon/Delicious etc. second... with Yahoo, MSN and Ask coming in on the pathetic third tier.
I've never encouraged a "Google First" or "Google Only" mentality for search marketers to follow. This is where you focus only on Google, figuring the other major search engines don't matter. Instead, I've said that all the search engines are important traffic channels to pursue. Don't forget the search engines beyond Google! But over the past few weeks, I've found myself more and more thinking that if you want to go beyond Google as a search marketer, the other search engines that matter first are the "social media search engines." After them come the other major general purpose search engines like Yahoo, Microsoft and Ask.
If anyone doubts it, check your referrers. Has Digg/Delicious/Stumbleupon sent you more traffic lately than Yahoo/MSN/Ask? I thought so...
If not, you're missing a huge opportunity!