DataFrame.ix with boolean arrays
Works right in one dimension but not both:

In [19]: df = DataFrame(np.random.randn(3, 2))

In [20]: df
Out[20]: 
          0         1
0  0.666325  0.812192
1  0.023781  1.719397
2  0.318738  0.227240

In [21]: df.ix[df.index==0, :]
Out[21]: 
          0         1
0  0.666325  0.812192

In [24]: df.ix[:, df.columns==1]
Out[24]: 
          1
0  0.812192
1  1.719397
2  0.227240

But not both:

In [23]: df.ix[df.index==0, df.columns==1]
Out[23]: 
              0         1
True   0.023781  1.719397
False  0.666325  0.812192
False  0.666325  0.812192
