The upcoming death of Google Reader and the addition of hashtags signal Facebook will likely launch a new way to discover and read news at the June 20th press event it’s just sent out mysterious invites to. It could be a sort of “trending articles on Facebook” feature, or a more full-blown RSS reader-style product. Either could take advantage of Facebook’s massive treasure trove of aggregate data on what people share to surface popular and personally recommended news articles. The event invite, first spotted by Joanna Stern of ABC News, says “A small team has been working on a big idea. Join us for coffee and learn about a new product.” The conspicuously analog invite was sent out via paper snail mail instead of by email like Facebook usually does. There’s also a coffee stain on the invite. You know where else you find coffee stains? On the newspaper, while you’re reading it, over coffee.