Thought this was interesting...
Vince McMahon and company, who have traditionally viewed MMA not as direct competition but rather the new 'boxing', may be having a change of heart according to Dave Meltzer of the Wrestling Observer. WWE has rather quietly started instructing arenas housing WWE events to not permit MMA events at their venues either 30 days before or after a WWE event.
This was a strategy used by Vince McMahon in the 1980's when the WWF was first expanding nationally. The idea was to push the regional promotions into smaller venues to make the WWF look more big time.
Extreme Fight Night, an Atlanta-based MMA group, have already moved three dates this year upon pressure from WWE.Source