Add note about xgrid support being broken.

This commit was SVN r23060.

README

@@ -158,7 +158,7 @@ Known issues
 ===========================================================================
 
 The following abbreviated list of release notes applies to this code
-base as of this writing (14 January 2010):
+base as of this writing (28 April 2010):
 
 General notes
 -------------
@@ -363,6 +363,10 @@ General Run-Time Support Notes
 
   http://www.open-mpi.org/community/lists/users/2006/01/0539.php
 
+  *** NOTE: Open MPI's XGrid support is known to be broken in the 1.3
+      and 1.4 series.  Are you an OS X developer?  We'd love to have
+      someone join us to fix this stuff.
+
 - Open MPI's run-time behavior can be customized via MCA ("MPI
   Component Architecture") parameters (see below for more information
   on how to get/set MCA parameter values).  Some MCA parameters can be