The new Gefen DisplayPort claims to send DisplayPort signals from computers (e.g., MacBooks, Dell, etc.) up to 45 meters (150 feet) away. The Booster, which measures approximately 2″x2″, sits between the long copper cable and the display, essentially boosting the signal to its final destination at resolutions up to WUXGA (1920×1200) resolutions. Gefen claims for higher resolutions up to 2560×1600, the DisplayPort Booster can double the specified distance of DisplayPort up to 100 feet (30 meters). HDCP compliance and EDID information are also transmitted for an impeccable performance at the extended location.
In most cases, the Booster will not require power to operate, drawing its power from the source. In the instance that the source is unable to power it, the Booster comes with a 5-volt power supply.
Here are all the specs: http://www.gefen.com/kvm/ext-dp-141b.jsp?prod_id=10779