std::locale does not work here

[Patrick Gräbel]

I am using Cygwin (g++-3.3.1) and Debian/stable (g++-3.0.1). The 
following call will not throw an "runtime_error" that is described in 
Stroustrup's C++ bible:

std::locale loc("$$§§§XXXYYY????!!!");

The constructor even accepts locale strings, that do not make sense. 
Also the following code will _not_ produce a ',' instead of a '.':

std::locale loc("de_DE");
double d = 1.76;
std::cout.imbue(loc);
std::cout << d << std::endl;

That's weird. Is g++'s stdc++ lib incompatible to the standard?

Please help me!

-Patrick