Draw a vertical line along the east edge of the south pool. Draw a horizontal line through the center of the north pool. Where they intersect is the original location of the sphere - on the Greenwich St sidewalk outside the museum building.
The question as to whether the sphere would return to the site was brought up at Ask the Port Authority. See the last question. The answer makes it obvious that if the sphere returns, it will be placed within the museum. I checked around the museum site, and found nothing.
I think the sphere is fine where it is in Battery Park. It shares space with other memorials, so it's not out of place. Occupies a prominent spot on the mall, and it's anything but ignored. This section of Battery Park is slated for a renovation.
http://www.flickr.com/photos/hbomb/11621758/

