"We can say little, if anything, about what these patterns [above] signify, why they were cut into rocks, or who created them. For all intents and purposes, they might have been made by aliens." When a new NASA book on alien communications has a paragraph like that, you better pay attention. Update 2: NASA pulled the book and press release from their site. Now the book is available here, as pointed out by a commenter."
Keith's note: Someone found a book "Archaeology, Anthropology, and Interstellar Communication" online at NASA.gov - one that NASA paid for, published, and posted. At one point it off handedly talks about aliens leaving messages on rock. So NASA pulls it offline. Now, people reading the articles that refer to the book get a dead link [update: NASA put the book back online so the link works again]. Well, nothing ever really disappears on the Internet. You can download the book here. Duh.
Keith's update: Classic NASA explanation below. NASA should post it on NASA.gov - at the links that news articles have been linking to so that all the people coming to visit the broken link see the real reason. When NASA just pulls things offline with no explanation it simply fuels these sort of stories. Without the original document online no one can see the context that NASA wants you to refer to. So they go with what NASA has left there - a big gapping hole.
William P. Barry, D.Phil. NASA Chief Historian "re: http://nasawatch.com/archives/2014/05/nothing-disappe.html where you assume that we are trying to hide something. What actually happened was that our publication production support contractors were preparing our free ebook download page for the "roll out" of our latest book in early June. That web page was supposed to be saved for review, but instead it was mistakenly published to the web. I noticed this within an hour of the accident and asked our folks to pull the page from the web. Unfortunately, turning the page off took a lot more time than putting it out there. In the interim the book generated some web buzz based on taking a sentence in it out of context. (Read the passage more carefully, the author of that chapter is not suggesting that aliens left a message on a rock.) The process of removing the ebook page from the web had nothing to do with the rather sloppy and florid online stories. We still plan to release the book in early June. The pacing item is delivery of the hard copy books - which are currently at the printer and scheduled for delivery no later than June 9. The PDF and ebook versions that were mistakenly made available on Tuesday evening are exactly the same as the versions that are at the printer and that will be fully available again when we release the book as scheduled in June. No government conspiracy, just a fat finger mistake, and my attempt to make the release go according to plan. I'd appreciate it if you would correct your web item above."