bus from Nairobi to Johannesburg

I'm looking for a bus connection from Nairobi, Kenya to Johannesburg, South Africa.
Does anyone know about it?
Who operates? What does it cost? How long does it take? Any other relevant issues?
Thanks for your comments.

There are buses which travel from Nairobi to Dar where you can connect to South Africa.
And there were some other buses which were travelling upto Harare and Lusaka where it would be easier to connect to SA.
Email me so that I could check for you

Good!
you can take a direct bus from Nairobi to Lusaka Zambia. the name of this bus is called Scandinavia. you can get it from River Road Nairobi, behing a kamba bus.
From Lusaka zambia, the City to City Bus leaves at 1.30pm.
The bus from nairobi will charge you $100 and from lusaka to Jo'burg is 250,000 kwacha equivalent of $80
I hope you got what you wanted, nice trip, am also taking Scout on 27th of November

Rays of Good Hope International volunteers
(ROHIV)
P.o Box 7748-00200
Nairobi
Kenya.
Fax 0203878342
Raysofgoodhope@gmail.com

How Long Is The Bus Ride? And how safe is it?

I've taken the plane, but I'd love to take the scenic route the next time.

Thanks!