Bug 322840 has appeared again. It described by the comment in rdesktop (http://rdesktop.cvs.sourceforge.net/viewvc/rdesktop/rdesktop/xwin.c?view=markup#l_552):

  552 /* Wait for a ConfigureNotify, with a equal or larger serial, on the
  553    specified window. The event will be removed from the queue. We
  554    could use XMaskEvent(StructureNotifyMask), but we would then risk
  555    throwing away crucial events like DestroyNotify.
  556 
  557    After a ConfigureWindow, according to ICCCM section 4.1.5, we
  558    should recieve a ConfigureNotify, either a real or synthetic
  559    one. This indicates that the configure has been "completed".
  560    However, some WMs such as several versions of Metacity fails to
  561    send synthetic events. See bug
  562    http://bugzilla.gnome.org/show_bug.cgi?id=322840. We need to use a
  563    timeout to avoid a hang. Tk uses the same approach. */

It's easy to verify if the problem is present, just run "rdesktop -A someserver" (with rdesktop later than 2008/03/26). It will print:

WARNING: Broken Window Manager: Timeout while waiting for ConfigureNotify
WARNING: Broken Window Manager: doesn't handle restack (window was moved to bottom)

I've confirmed the problem with metacity-2.24.0-2.fc10.i386 and I've got reports from Debian Lenny.