This is an excellent development - The Big Picture from boston.com, a beautiful photo blog and one of the big reasons for putting ReaderScroll together, has implemented j/k navigation, inspired by ReaderScroll. Nicely done - now you can navigate the pictures via the j/k keys.
One down, many more to go. First step towards j/k navigation everywhere.
Btw, several people have pointed out vi used j/k navigation before Google Reader. True enough. j/k was also used in very old keyboard based games. However, the use of j/k to center web content was first brought to my attention in Google Reader, so I’m sticking with “Google Reader Style” instead of “vi style”.