Isn't this essentially scrapping content from other web sites with out their permission, removing all the ads, and then presenting them in a nice way. I always assumed this was not allowed?
IANAL, but I have a feeling, its NOT OK (both legally and ethically) for a commercial to redistribute the content (without taking prior permission/licensing, that is), deviating the original creators from revenue/traffic et al.
But I'm not sure if this is true. Scraping is scraping, regardless whether or not you link to it.
In the last paragraph you can find this though "Flipboard hasn’t worked out a business model yet, but plans to put ads next to articles and then share some advertising revenue with publishers." Which indicates they do acknowledge the publishers for the content and want to share (potential) revenues with those publishers.
By that logic, Google and other search providers' services should be up for scrutiny.