Lambda expressions as class template parameters

Can lambda expressions be used as class template parameters? (Note this is a very different question than this one, which asks if a lambda expression itself can be templated.)

I'm asking if you can do something like:

template  
struct Foo { };
// ...
Foovoid { })> foo;

This would be useful in cases where, for example, a class template has various parameters like equal_to or something, which are usually implemented as one-liner functors. For example, suppose I want to instantiate a hash table which uses my own custom equality comparison function. I'd like to be able to say something like:

typedef std::unordered_map<
  std::string,
  std::string,
  std::hash,
  decltype([](const std::string& s1, const std::string& s2)->bool 
    { /* Custom implementation of equal_to */ })
  > map_type;

But I tested this on GCC 4.4 and 4.6, and it doesn't work, apparently because the anonymous type created by a lambda expression doesn't have a default constructor. (I recall a similar issue with boost::bind.) Is there some reason the draft standard doesn't allow this, or am I wrong and it is allowed but GCC is just behind in their implementation?