sys-apps/dbus-0.50-r1 does not set the qt 3 directory correctly, and so tries to build against and link to qt4 if it is installed. This is probably true of all versions of dbus, but this is the first version I spotted the failure on. The fix is fairly trivial - I will attach a diff. As qt4 is now in the testing tree this patch is required for a testing system with qt4 present.
Created attachment 73153 [details, diff] dbus-0.50-r1.diff
Created attachment 73154 [details, diff] dbus-0.50-r1.diff Try again - added else to disable qt if it is not set too...
This should now be fixed in dbus-0.50-r1 (v 1.2).