Mashable.com reported today numbers from Compete.com showing how Bing’s traffic has spiked, with Bing now passing Twitter, Digg, and CNN in terms of traffic. A number of sites have related posts, but there seems to be another story in the numbers.

As we’ve discussed in previous posts, Microsoft’s main competitor today is not Google, but Yahoo. Only after Microsoft can pass Yahoo can it challenge Google. So, what do Compete’s numbers tell us about this competition? First, note that Yahoo (unlike Google) is much more than a search engine; it is a portal with a busy home page contain news, search, email, weather, and more. Therefore, it really is more comparable to the sum of msn.com (or live.com) and bing.com than to any one individually.

So, how does it compare? Looking at the below chart from Compete.com, the first thing that is apparent is that Microsoft has closed the gap with Yahoo since the beginning of the year. Next, if you add up live.com and bin.com’s traffic compared to Yahoo’s, in the month of June they SIGNIFICANTLY closed the gap.

However, I’m not sure how Compete adds up its numbers for Microsoft. For example, live.com redirects to bing.com but mail.live.com does not. Moreover, msn.com more closely competes with yahoo.com’s news and weather features. And searches on msn.com go to bing.com’s results page. Regardless, it’s interesting to see all of Microsoft’s sites.

Even ignoring live.com’s traffic, the sum of msn.com plus bing.com significantly exceeds Yahoo’s traffic (with the above caveats noted).