UTD, UTA, UNT, SMU, TCU, TWU - lots of higher ed here - entry level labor for growing companies. That graphic says a lot, but it doesn't say anything about the speed at which this community is coming together. I just moved back from Boulder, and I can tell you that Dallas has every bit of the activity and passion.
Stabile Economy. Natural resources & lessons learned from previous housing busts insulated Dallas (relatively) from the '08-'09 global meltdown.
International connections via fabulous airports, centrally located in USA, cheap labor, can-do spirit, business friendly politics, not freezing weather, and it's where JR called home :) reasonable media/advertising companies.
Houston is a cool bro too. Better food, more people, more bars, cheaper housing.<p>EDIT: Rice and UH are both fantastic schools for research and business, respectively. And we've got the largest medical center in the world.