Sorry, I should have written this more than one day ago, but time flies at the Canonical conference.
As the GNOME team seems to have GNOME 2.6 more or less sorted out for Sarge, it was time to break something else. As breaking unstable is not the greatest idea now, the obvious target was experimental. :) It's not a "oh fuck, my desktop died entirely" problem, but it could affect Nautilus users quite a bit. Two days ago, gnome-vfs2 2.7.90 was uploaded, thus switching Debian's GNOME 2.7 to Free Desktop's MIME type format. Applications need to be updated to use the new system (which needs some registering in postinst) before nautilus will recognize the MIME types they provide. So the biggest problem you'll find is that stuff like gedit doesn't open when you click on a text file in nautilus, etc. This is being fixed right now, but it'll take some days to have it done. Fortunately, we have the patches Ubuntu has kindly provided, which will ease this task a lot.
On a related note, and as I said above, Sarge is now only missing gnome-games and eog to complete the GNOME 2.6 transition. These are blocked by the exif/tiff transitions right now, but are not considered critical for the Sarge release. That means, if they don't make it in in time, they won't block the Sarge release. Anyway, we hope it'll be solved soonish, still. What we do probably want to stick in Sarge whatever it takes is GIMP 2.0.x. The current version in testing is quite unacceptable.