The "call" example included in the Telepathy-Qt4 sources has some issues:
1. The incoming audio stream is not played back.
2. The incoming video stream display's a still image of the first frame
3. The outgoing video stream does not work entirely

I am using Telepathy-Qt4 0.3.4 on a openSUSE 11.2. The following libraries are installed:
- libtelepathy 0.3.3
- libtelepathy-farsight0 0.0.11
- libtelepathy-glib0 0.8.0
- farsight 0.1.28
- libfarsight2_0 0.0.20
- gstreamer-0_10-plugins-farsight 0.12.11
- libgstfarsight-0_10-0 0.0.16

I'm working on an instant messanger (Peregrine) and got audio streaming to work properly. The outgoing video stream is still not working. I dumped the running GStreamer pipeline into a dot-file. The sink pad from the FsRtpConference element that I connect the video stream to is only connected two more elements:
GstTee, GstValve
so nothing is done with the video streamed to the FsRtpConference element.
(See attachment. You can create a PNG file from that dot file by running:
#> dot -Tpng -o0.01.30.881504190-pipeline_dump.png 0.01.30.881504190-pipeline_dump.dot
)