It's an option as part of the Performance pack, I've ordered an estate, so I'm not likely to see that towards the end of the year, but I really don't want racing brakes 19" wheels etc, which it appears I have to have to enjoy an LSD.
I actually think it's ridiculous it's not standard.
Although in a way I agree, generally LSDs have a shorter working life than open diffs, whereas the electronics just wear out your rear brakes. Also I think that if your driving style necessitates an LSD then the bigger brakes are probably essential too, and the 19" rims probably to accommodate the brakes...
At night with the lines and lights all a blur my passengers sometimes think they've popped LSD.