The recent attempted in-flight bomb attack by a Nigerian national means that racial profiling of terrorists based on previous cases cannot merely be restricted to Arab Muslims, but also African Muslims. At this rate, it's only a matter of time before Asian and Caucasian militants are employed to get past airport screening. Back in September, Pakistan reported encountering a village of white expat German radical Muslims near the Afghan border.
Update: In 2007, two members of a bomb plot in Germany were white German nationals who had converted to Islam. Combined with the potential from Indonesian Islamic militants, no race can be ruled out as a potential threat.