Currently in beta, Amazon Author Insights features the advice of many published authors including Hugh Howey, Joanna Penn, Bryan Cohen, and Elizabeth S Craig as well as a number of articles by Amazon’s staff (under the byline Kindle Press).
The site is hosted on Tumblr, and is divided into three sections: Write, Publish, and Market. There’s also a fourth section which claims to focus on tools and services, but really just lists various Amazon services (KDP, Createspace, Kindle scout, Goodreads, etc).
Amazon has not announced the site yet, and it’s not clear what they’re trying to accomplish here. But the articles I read all contained sound advice, so the site is definitely worth checking out.