Bit-Tech published a feature looking into DisplayPort. Here's a taster:

Electrically, the interface is similar to PCI-Express' physical layer connection and is what's known as an AC-coupled voltage-differential interface. It consists of three different channels: main link, AUX channel and hot plug detect. The main link features one, two or four scalable data pairs (or lanes) fixed at either 1.6Gbit/sec or 2.7Gbit/sec. The main link rate will be determined by a number of factors, including the capabilities of the transmitter and receiver (i.e. Display and Graphics Card) and the quality of the cable.

With DVI, there was a separate pair of lanes responsible for maintaining the data clock, but with DisplayPort the clock is embedded into the data pairs and is extracted from the encoded data stream itself. In the past, colour channels were split over data pairs, but each lane in the DisplayPort interface is decoupled from both the pixel bit depth (bits per pixel, bpp) and the component bit depth (bits per component, bpc). The link supports component bit depths from six (18-bit RGB) to sixteen (48-bit RGB) – it's questionable whether you'll see much difference in quality once you get past 10bpc, but that's beyond the scope of this article.