jhbuild on Fedora

Hi --
	I've been blocked on this for a while now, partly by my stubborn insistence that someone must have been running into this, posted a query and received an answer on how to fix this.  If that's happened, I haven't found it.
	So…
	I've got Fedora 15 x86_64 running on my machine, have been using jhbuild to get pretty much everything built, then following the steps listed at http://developer.gnome.org/jhbuild/unstable/jhbuild-and-gnome.html.en to set up gnome to run in a nested window.  Xephyr runs fine but when I try to start up gnome it fails miserably.  Rather than piping stderr to /dev/null I'm just letting it spew out to the console.  The following error messages are listed:

---
gnome-session[17574]: WARNING: Could not make bus activated clients aware
  of DISPLAY=:2 environment variable: Did not receive a reply.
  Possible causes include: the remote application did not send a reply,
  the message bus security policy blocked the reply, the reply timeout
  expired, or the network connection was broken.
gnome-session[17574]: WARNING: Could not make bus activated clients aware
  of GNOME_DESKTOP_SESSION_ID=this-is-deprecated environment variable:
  Did not receive a reply. Possible causes include: the remote application
  did not send a reply, the message bus security policy blocked the reply,
  the reply timeout expired, or the network connection was broken.
gnome-session[17574]: WARNING: Could not make bus activated clients aware
  of SESSION_MANAGER=local/unix:@/tmp/.ICE-unix/17574,unix/unix:\
  /tmp/.ICE-unix/17574 environment variable: Did not receive a reply.
  Possible causes include: the remote application did not send a reply,
  the message bus security policy blocked the reply, the reply timeout
  expired, or the network connection was broken.
---

	Inside the Xepyr window, after a long delay, the following error appears:
---
Could not connect to session bus: Did not receive a reply. Possible causes
  include: the remote application did not send a reply, the message bus
  security policy blocked the reply, the reply timeout expired, or the
  network connection was broken.
 [ _L_og Out ]
---

	I'm guessing that "the message bus security policy blocked the reply" is the critical link and that there's something specific to Fedora distributions that I have to jiggle to get this whole thing working.  What, pray tell, is it?
	Extra points to an existing link that answers this question in the hope that it will get the corresponding page's search rank to be raised a couple of points and spare someone else the same agita in the future.  TIA.