Ok, some folks have the strategy guide, and maybe it answers this question. What spells can a Mirror Image cast? The MI description says the images can cast "some" of the same spells as the wizard.
When runed with the Mirror Mimic rune the images do a small amount of damage. Can Mirror Mimics cast crowd control type spells, like Frost Nova if the wizard knows the spell? It would be nice to know exactly what they are capable of casting to try to make a synergized build.
Here is an idea for a solo build if MMs can cast spells like Frost Nova and Wave of Force. It might be a bit chaotic, but it would be fun. Definately not a build for parties with monsters flying all over the place.
Unfortunately, the guide doesn't say which spells the images are allowed to cast. However, it does confirm that they can't use all the skill of the Wizard. In a short explanation about the damage of the Mirror Mimics the guide uses Energy Twister as an example, so I assume the images can use it. We already seen them use signature skills, Arcane Orb and Frost Nova as well, but I doubt their FN will freeze enemies.
Another interesting thing is that the guide says that the images copy our every move, which wasn't true at all in the previously released videos. The images always behaved like pets, running around and attacking enemies randomly with whatever spell they decided. This behavior makes them completely useless for PvP, but if they would really copy our spells and attack our targets that would be amazing. I doubt they will work that way though, the guide probably means that they choose from the spells we have with us.