Very recently -- in the 90's -- the repulsive connotation has receded and the brainy factor has come to the fore.

hence Nerd?
And did you see the PBS program "Revenge of the Nerds?"
The SOED says "an insignificant or foolish person, a person who is boringly conventional or studious."
So how'd it come to mean "smart, clever in electronic medium, and rich-beyond-your-wildest-dreams?"

Are you lurking Bill Gates?