The GlassUp eyeglasses
report the incoming e-mails, text messages, tweets, Facebook updates, and other messages, so that the rider "can keep abreast on what is going on in this big world." The message is shown for only a few instants, on the side of the field of view, in an unobtrusive manner.
They work via a bluetooth connection and a set of apps (Android and iOS), depending on the mobile platform and the message you want to receive, so you must have your mobile with you. They are designed for read-only.
We keep a phone in the hydration pack but wouldn't want the distraction of the GlassUp on an intense downhill. Still, we could see where a professional like a doctor who needs to keep in touch or a race team manager might find the GlassUp a valuable tool. The GlassUp will set you back $299 and the company is taking preorders.