I personally would like to see an option such as this, along with many other chat options. A whole host of chat filtering/highlighting options are planned, once we have a proper chat settings interface (instead of the blocking browser popups currently used).
Sadly, at the moment, I and most other devs are preoccupied with other projects. BTTV is not really seeing anything but bug fixes. The Github repo is here. (Keep in mind, any new features would have to be looked over and approved by night.)