Thanks Owain,
From which I infer that the current Airbus FBW provision to comply with the JAR is the aural element.
A stick shaker or vibrator of some kind seems worthy of consideration, but would have no tactile effect unless and until the pilot took hold of the side-stick. So the initial warning would remain aural. (I'm not sure that a chair-shaker would be either acceptable or efficacious!)
safetypee writes of the BAe 146, and the stick-shaker/vibrator would not be greatly different from traditional types with which I'm familiar (VC10, B707, BAC 1-11, A310, DC10), except that the sidestick is so much smaller than their control-column/wheel combination.
Perhaps the stick vibration could be made to increase if the pilot pulls up...