So what's the situation in California? Prop 8 is facing 3 lawsuits to repeal it. What are those 3 lawsuits?

The three lawsuits are all separate ones that are making the same point that you referenced above, they have just been filed separately. Currently, the marriages are still legally valid, the Courts would need to decide that they have been invalidated before they will be nullified. Prop. 8 took effect immediately upon certification of the results, although some counties are going to continue issuing marriage licenses while it is being challenged in court.