Shall we go for the high level summary?
It seems likely many people simple noticed for the first time long-standing redirection that Google had in place for those not using Android or iOS devices
After looking at the coverage, Sullivan puts forward one potential explanation of why people did not pick up on this issue before:
It’s possible that people have been getting routed into Bing Maps rather than Google Maps [when looking at search results, because IE turns addresses into links pointing at Bing maps on the device]... (in part because Google itself fails to direct them there) and so never encountered the redirection that Google says has long existed. As far as they knew, they were going from Google into what they might have assumed was Google Maps. It’s not like you can immediately tell a big difference.
Add in lots of people looking for a story, the recent noises that Microsoft have made towards Google and access to YouTube, and then reports that Google had [apparently] taken away access to the mobile version version of Maps from Windows Phone handsets... and you have the perfect storm for the weekend.
The actual story appears to be a little bit more mundane, with a mix of false perceptions, a helpful OS creating extra links, and people unaware that what Google are doing with mobile devices, including Windows Phone, is what they've been doing for rather a long time.
Of course this doesn't mean that Google shouldn't be treating Windows Phone better, or that some of Google's explanations were a little disingenuous, but it's likely not the evidence for the existence of the evil-Google-to-kill-plucky-little-Windows-Phone masterplan that some have suggested.