Today Player.net posted an article detailing the announcement of Noctua's two newest fan lines: the Redux series and the Industrial series. Each of these fans addresses new segments of the market to provide not only more specific products for more specific needs, but to also address the public outcry for fans of a different color. The Redux line sports a gray frame with black blades and is targeted at those who wish to enter the world of premium case fans but don't have the cash for the top shelf gear, while the industrial lineup is geared towards enterprise use with it's 3k RPM peak and emphasis on extreme performance. The latter fans are colored all black with dark brown rubber vibration dampers.
Noctua Introduces Two New Fan Product Lines and Accessory Kits - Play3r
EDIT: 3K fan speed is specific to one particular fan, the rest in the lineup peak at 2k.