Mine

>>> variable="progrAmacIon"
>>> diccionario={'a':0,'e':0,'i':0,'o':0,'u':0}
>>> for letra in variable.lower():
...     if letra in diccionario.keys():
...             diccionario[letra]+=1
...
>>> for elemento,valor in diccionario.items():
...     print "%s = %i" % ( elemento, valor)
...
a = 2
i = 1
e = 0
u = 0
o = 2
>>>