This is the Protoss tech tree that was exhibited at Blizzcon. Text comes from Gamespot.

New structures included the null circuit, dark obelisk, phase prism, and twilight council buildings which all tied into the new units. We tried our hand with as many of them as we could build and were intrigued by what we played. Null circuit buildings are one part of the equation to let you summon the observers to be constructed.
The dark obelisk allows you to make dark templars, and phase prisms let you do create the mighty colossus, a killer land unit shown previously. The twilight council lets you create immortals. In addition the stargates let you summon the new phoenix and warp ray craft as well as the old standby, the carrier.