Selection of GI techniques working in real time
In this vein a bit, Killzone renders one bounce reflections, but uses temporal anti aliasing to combine the last frame with the current frame.

In practice, this means you get MANY bounce reflections, since in effect each frame rendered catches the previous number of reflections as the new reflection - adding one each frame.

Not quite GI, but i wouldn't be surprised if people pursue that direction more in the future, if they aren't already working on it.

The temporal anti aliasing used normally lets you get more samples with subsequent frames, but used in this way, it also gives you higher bounce counts with subsequent frames.

I could totally see doing path tracing type path following, choosing reflection or BSDF rays based on fresnel equations for instance, and having the temporal AA combine it over time.