Not apples to apples. The number you cited for the MBP is taken from a 32 bit test whereas the MBA (from Laptop Mag's test) was running a 64 bit test.Impressive...
MBP 13 i5 (2011): 5917
MBA 13 i5 (2011): 5860
It should actually be:
MBP 13 i5 (2011): 6448
MBA 13 i5 (2011): 5860
So there's still a ~10% difference, at least in this synthetic benchmark. And it's also worth noting that the ULV SB processors have a very aggressive turboboost setting which probably wouldn't be sustainable in extended real world circumstances (heat, etc).
These results are still impressive, but I'd wait for real world tests before jumping to conclusions.
Note: the 11" MBA running the 1.6 GHz i5 scored just 5060. The main reason? A paltry 2.3 GHz boost vs. the 1.7 GHz model's 2.7 GHz peak.