At the Ambisonics Symposium 2010 (hosted by IRCAM in Paris), I presented a paper on using a 3rd-order Ambisonic rig to present non-Ambisonic electro-acoustic works with virtual speakers.
The paper is intended as a how-to for people who wish to employ similar techniques for their own concert events. It includes a report on informal listening tests that might be interesting as a starting point for further study.

Grab the paper at http://stackingdwarves.net/public_stuff/linux_audio/ambisonic_symposium_....
Slides are available at http://stackingdwarves.net/public_stuff/linux_audio/ambisonic_symposium_..., and there's a video of the presentation from LAC 2010 at http://stackingdwarves.net/public_stuff/linux_audio/lac2010/day2_1130_Ge....