Now boolean operators work with NDFrames?
Awkward side effect of the new and improved `Series` probably, I typed something wrong and was shocked to not get the usual `numpy` `ValueError` barf:

```
In [57]: a, b = Series(rand(10) > 0.5), Series(rand(10) > 0.5)

In [58]: a
Out[58]:
0     True
1     True
2    False
3    False
4     True
5    False
6    False
7     True
8     True
9     True
dtype: bool

In [59]: b
Out[59]:
0     True
1     True
2     True
3     True
4    False
5     True
6    False
7     True
8     True
9     True
dtype: bool

In [60]: a and b # what?! no way!!
Out[60]:
0     True
1     True
2     True
3     True
4    False
5     True
6    False
7     True
8     True
9     True
dtype: bool

In [61]: a & b # whew
Out[61]:
0     True
1     True
2    False
3    False
4    False
5    False
6    False
7     True
8     True
9     True
dtype: bool
```
