How do I hook a new Mac Book Pro Retina up to dual DisplayPort monitors?
From EveryMac…


  This model supports a simultaneous maximum resolution up to 2560x1600 on two external displays via Thunderbolt. Alternately, it can support a single display up to 2560x1600 via Thunderbolt and a single 1080p display at up to 60 Hz, 3840x2160 at 30 Hz, or 4096x2160 at 24 Hz via HDMI.


If you have 2 Thunderbolt ports, you can use 2 miniDP to Display Port cables, one from each port, just as though the ports were miniDP as they are backwardly-compatible.

See Thunderbolt ports and displays: Frequently asked questions (FAQ)