Series Changes breaks rpy2?
It seems that the changes to to Series break the data conversion to R: running this Notebook doesn't work anymore with some dev version from last week:
https://gist.github.com/kevindavenport/7771325/raw/87ab5603f406729c6a3866f95af9a1ebfedcf619/Mahalanobis_Outliers.ipynb

The resulting error is this:

``` python
#xydata=pandas.DataFrame(...)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-38-74fcaa767ca0> in <module>()
----> 1 get_ipython().run_cell_magic(u'R', u'-i xydata,xycols # list object to be transferred to python here', u'install.packages("ggplot2") # Had to add this for some reason, shouldn\'t be necessary\nlibrary(ggplot2)\ndf = data.frame(xydata)\nnames(df) <- c(xycols)\nprint(head(df))\nplot = ggplot(df, aes(x = X, y = Y)) + \ngeom_point(alpha = .8, color = \'dodgerblue\',size = 5) +\ngeom_point(data=subset(df, Y >= 6.7 | X >= 4), color = \'red\',size = 6) +\ntheme(axis.text.x = element_text(size= rel(1.5),angle=90, hjust=1)) +\nggtitle(\'Distance Pairs with outliers highlighted in red\')\nprint(plot)')

C:\portabel\Python27\lib\site-packages\IPython\core\interactiveshell.pyc in run_cell_magic(self, magic_name, line, cell)
   2141             magic_arg_s = self.var_expand(line, stack_depth)
   2142             with self.builtin_trap:
-> 2143                 result = fn(magic_arg_s, cell)
   2144             return result
   2145 

C:\portabel\Python27\lib\site-packages\IPython\extensions\rmagic.py in R(self, line, cell, local_ns)

C:\portabel\Python27\lib\site-packages\IPython\core\magic.pyc in <lambda>(f, *a, **k)
    191     # but it's overkill for just that one bit of state.
    192     def magic_deco(arg):
--> 193         call = lambda f, *a, **k: f(*a, **k)
    194 
    195         if callable(arg):

C:\portabel\Python27\lib\site-packages\IPython\extensions\rmagic.py in R(self, line, cell, local_ns)
    585                     except KeyError:
    586                         raise NameError("name '%s' is not defined" % input)
--> 587                 self.r.assign(input, self.pyconverter(val))
    588 
    589         if getattr(args, 'units') is not None:

C:\portabel\Python27\lib\site-packages\rpy2\robjects\functions.pyc in __call__(self, *args, **kwargs)
     84                 v = kwargs.pop(k)
     85                 kwargs[r_k] = v
---> 86         return super(SignatureTranslatedFunction, self).__call__(*args, **kwargs)

C:\portabel\Python27\lib\site-packages\rpy2\robjects\functions.pyc in __call__(self, *args, **kwargs)
     29 
     30     def __call__(self, *args, **kwargs):
---> 31         new_args = [conversion.py2ri(a) for a in args]
     32         new_kwargs = {}
     33         for k, v in kwargs.iteritems():

C:\portabel\Python27\lib\site-packages\rpy2\robjects\pandas2ri.pyc in pandas2ri(obj)
     26                 od[name] = StrVector(values)
     27             else:
---> 28                 od[name] = ro.conversion.py2ri(values)
     29         return DataFrame(od)
     30     elif isinstance(obj, PandasIndex):

C:\portabel\Python27\lib\site-packages\rpy2\robjects\pandas2ri.pyc in pandas2ri(obj)
     49         else:
     50             # converted as a numpy array
---> 51             res = original_conversion(obj)
     52         # "index" is equivalent to "names" in R
     53         if obj.ndim == 1:

C:\portabel\Python27\lib\site-packages\rpy2\robjects\numpy2ri.pyc in numpy2ri(o)
     56             raise(ValueError("Unknown numpy array type."))
     57     else:
---> 58         res = ro.default_py2ri(o)
     59     return res
     60 

C:\portabel\Python27\lib\site-packages\rpy2\robjects\__init__.pyc in default_py2ri(o)
    146         res = rinterface.SexpVector([o, ], rinterface.CPLXSXP)
    147     else:
--> 148         raise(ValueError("Nothing can be done for the type %s at the moment." %(type(o))))
    149     return res
    150 

ValueError: Nothing can be done for the type <class 'pandas.core.series.Series'> at the moment.
```

I'm not sure if this is something pandas cares, but even if not it would be nice to mention it in the release notes.
