I have been looking into information about females having an orgasm during intercourse. Recents studies, like the one mentioned in the LA Times article "Rule of Thumb" seem to indicate that it is entirely dependent on the C-V distance (clitoris to vagina).
"In fact, there's even an easy "rule of thumb," Wallen says: Clitoris-vagina distances less than 2.5 cm -- that's roughly from the tip of your thumb to your first knuckle -- tend to yield reliable orgasms during sex. More than a thumb's length? Regular intercourse alone typically might not do the trick."