A few issues you'd have to tackle. First being cost. As far as I know, most organizations having anything to do with the arts are strapped for cash and making a computerized music stand would necessarily be quite expensive. You might have a hard time finding enough buyers to justify the production costs. These devices would also likely be more fragile/stolen and subject to higher repair/replacement costs then pure metal ones. A display would also make the stand "top heavy" so you'd have to do something to lower the center of gravity of the stand. Finally, you'd have to contend with power. Battery operated ones would be subject to unexpected power outages and would require charging. Charging a full orchestra's worth of music stands would require a lot of outlets. Though if you have interest, the best technology that I can think of being used for this would be "eInk" (http://www.eink.com/). It only draws energy when a page is changed and can be very clear with high contrast similar to regular tree pulp/paper. It is also pretty light weight.

Current tablet PCs could easily be adapted for this, including a wireless network the conductor controls.

There is already special software for Tablet PC called MusicReader to turn it into a Electronic Music Stand.