Python 2.7.3 (default, Apr 27 2012, 21:06:39)
[GCC 4.7.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.

>>> import re

>>> def is_palindrome(i):
...  i=''.join(re.findall('[a-z0-9]+',i.lower()))
...  return i==i[::-1]
...

>>> print is_palindrome('Eva, can I stab bats in a cave?')
True

>>> print is_palindrome("Madam, I'm Adam Corolla.")
False

>>> print is_palindrome('A_man,_a_plan, a_caremer, a canal:_Panama!')
True