one of the major limitations is the capability (of currently any computer system really) handling the uncertainties that occur in the real world. there is some interesting work done in the area of human-machine co-habitation that deals with safety issues (as in physical safety for both humans and the machines sharing the same space) and strategies to react to unforeseen events. handling the general messy, noisy real world (even in a semi controlled environment like a house) is still a major limitation even if the robots could technically be capable of doing a specific chore