Months after its original announcement Mac RSS app Reeder 3 has made an appearance in the form of a public beta. Reeder 3, which will be available as a free update for Reeder 2 owners, features an updated interface, including a transparent sidebar, and an overall look more in tune with OS X Yosemite.
In addition the new interface, Reeder 3 features a number of useful updates, like unread and starred counts for your smart folders, private browsing support, and fullscreen support for minimized layout mode. The app has added full support for Instapaper for saving articles to read later, and more features from your favorite RSS services are now supported.
Keep in mind that while this is available publicly, this is beta software. As such, it's incomplete and things may be missing, or not work properly, and you may want to hold off until the official launch. Also note that because this is a beta release, many things could change by the time of the final launch.