I think that would depend on if you were trying to make an autonomous one, or a remote controlled one.
Autonomous would require some type of computer and mapping software that interfaced with some kind of sensors to report its position and objects in its way. Very complicated.
Remote controlled would just be a matter of picking up a self propelled mower, replacing the front wheels with pivoting wheels attached to some kind of solenoid to steer it, some type of solenoid for engaging the self propelling mechanism, and a remote sender and receiver. This could be very doable with some tinkering.
If they are anything like those vacuum bots, they will have quite a few years before they mature enough to really be useful. I've tried those vacuum bots in the past and they do an "ok" job, but the battery life on them is terrible. The constant recharging wears out those battery packs fast.