The bigger problem remains: lambda functions are hideous in Python. map() will forever be ugly if you try to use it in the same way it is used in most functional languages.
This sort of API is hard to implement in Python though, because there's no formal notion of interfaces, so you cannot extend all iterables generically. So you need to use free functions (which don't read well when chained) or a wrapper object (ick).
The bigger problem remains: lambda functions are hideous in Python. map() will forever be ugly if you try to use it in the same way it is used in most functional languages.