Regression in date formatting in IPython Notebook (v0.9-dev)
This is a possible regression in Pandas v0.9.0-667220a versus v0.8.1:

The following works, in both v0.8.1 and v0.9.0-667220a:

```
>>> from pandas.io.data import DataReader
>>> ts = DataReader("AAPL", "yahoo", start="01/01/2000")
>>> ts.head()

              Open    High     Low   Close    Volume  Adj Close
Date                                                           
2000-01-03  104.87  112.50  101.69  111.94  19144400      27.87
2000-01-04  108.25  110.62  101.19  102.50  18310000      25.52
2000-01-05  103.75  110.56  103.00  104.00  27818000      25.89
2000-01-06  106.12  107.00   95.00   95.00  27443200      23.65
2000-01-07   96.50  101.00   95.50   99.50  16463200      24.77
```

However, with v0.9.0-667220a, the graphical IPython Notebook output of the dates is garbled. In it, the dates appear as follows:

```
Date
1970-01-11 232:00:00
1970-01-11 00:00:00
1970-01-11 24:00:00
1970-01-11 48:00:00
1970-01-11 72:00:00
```

(I can attach a screenshot if someone can tell me how to upload or attach a file to an issue using GitHub...)
