ASRock and ECS have already announced the possibility to overclock Intel K-series CPUs on non-Z series motherboards, and now, unsurprisingly, it appears that more manufacturers are also announcing the feature.
Both Gigabyte and Biostar have announced the possibility of overclocking 4th Generation Intel Core K-series processors on H87 and B85 motherboards.
Previously, in order to overclock Intel CPUs through using the multiplier, there were two core requirements (beyond cooling and power). The two requirements were that you needed an Intel K-series CPU, as well as a Z-series motherboard. Now, while the former is still required, it is no longer necessary to have a Z-series motherboard in order to overclock your K-series CPU through using the multiplier.