The documentation for $.map has the following example:

 $.map( [0,1,2], function(n){
   return [ n, n + 1 ];
 });

It says that the result should be:

[0, 1, 1, 2, 2, 3]

However in version 1.1.2, the jQuery.map function has code to remove duplicates. The actual result from jQuery 1.1.2 is:

[0, 1, 2, 3]

Actually, looking at the trunk, it appears that this bug was already fixed with the code change in revision 1576, but I'm going to report it anyway, in case a regression test should be created.