Penrose Limit of N=1 Gauge Theories
  We find a Penrose limit of AdS_5 x T^{1,1} which gives the pp-wave geometry identical to the one that appears in the Penrose limit of AdS_5 x S^5. This leads us to conjecture that there is a subsector of the corresponding N=1 gauge theory which has enhanced N=4 supersymmetry. We identify operators in the N=1 gauge theory with stringy excitations in the pp-wave geometry and discuss how the gauge theory operators fall into N=4 supersymmetry multiplets. We find similar enhancement of symmetry in some other models, but there are also examples in which there is no supersymmetry enhancement in the Penrose limit. 
Jaume Gomis and Hirosi Ooguri