There are still locking problems with the a11y code. This is with ekiga 2.0.7 and at-spi 1.18.0
http://bugzilla.gnome.org/show_bug.cgi?id=329454 has a patch which is supposed to fix it. Unfortunately, b.g.o is down atm.
I hope that htis is fixed in at-spi-1.18.0-2.fc7