Microsoft held a Global Preview Event on September 19 and 20 for the new Microsoft Flight Simulator, and it's been NDA'd until today. Here's the official blog post, which doesn't say much itself, but there are a ton of detailed impressions articles and videos all over the internet today.
The major revelation is that they're using satellite data from Bing Maps and combining it with procedural generation and some other data sources (such as the ability to use live weather data) to make it so you can fly anywhere in the world and it will look extremely realistic. Being able to do this in Google Earth is already very cool (especially in VR), and this should be even better.
Here are a few of the articles - a lot of them have incredibly stupid titles because that's how internet journalism works now, so I'm just going to link with the site's name: