I just found out that starting in June 2009 Delta will be making some serious changes to their Africa flights. You can fly direct Atlanta=>JoBurg and more importantly, you can fly Atlanta=>Dakar=>Nairobi. This will likely be a bit faster than BA via UK. Of course if you’re leaving from Dallas, the BA flight is still probably your best bet, unless you just like flying Delta. Anyways, just one more option to get to Kenya from the States.

Read more about the changes at Delta’s wiki page. Scroll down toward the bottom where the flights are listed to see the details.