Strings in Ruby vs. C#

In Ruby:

s1 = "string"
s2 = s1
s2 << "a"
s1.should == s2

In C#:

string s1 = "string";
string s2 = s1;
s2.Insert( 0, "a" );
Assert.NotEqual( s1, s2 );

Strings in C# are immutable. So trying to change a string actually creates a new string. So updating s2 does not update s1.

Strings in Ruby are mutable. So strings in Ruby act like pointers and s1 is updated when you update s2.

UPDATE 1/19/2011:
To be more clear, here are some more examples of how Ruby behaves:

s1 = "string"
s2 = s1
s2 += "a"
s2.should_not == s1

s1 = "string"
s2 = s1
s2.gsub!('s','z')
s2.should == s1