If you like the idea of cycling gloves with turn-indicating LEDs on the back, then you'll probably like Zackees, which have been around for a few years now. You do need to activate those LEDs yourself, however, by touching a contact in the thumb of the glove to one in the index finger. If that's just a bit too much of a bother, then you might prefer a pair of beSEENs.
Unlike Zackees, each beSEEN glove contains a motion sensor that detects when the user's hand has moved from being on the handlebars to being held out in a turn-indicating position. The seven amber LEDs in that glove will then start flashing, and keep doing so until the hand is back on the bars again. Users can also set the LEDs to remain on constantly, so the gloves act more as running lights.
The beSEEN's LED/electronics modules are waterproof and removable, with one USB charge juicing them up for about seven hours of continuous use. The gloves themselves are machine-washable.
Motion detector-activated bicycle turn indicators aren't an entirely new idea, incidentally. Similar tech has been implemented in the Intelligent Blinker bracelet prototype and the still-in-development Useeme bracelet, and is currently used by the bracelet-activated TurnCycle indicator.
If you're interested in getting a pair of beSEENs, the Melbourne, Australia-based designers are currently raising production funds on Kickstarter. A pledge of AUD$70 (about US$55) will presently do the trick, with delivery scheduled for August, assuming everything works out. The estimated retail price range is $89 to $99.