Maybe something new has happened which I've never heard about, but my understanding has always been that many experiments have always yeilded the result that gravity was instantaneous within the error bounds of measurement.
Apaprently the final word hasn't been issued to the rest of the scientific community. Or to any of it. The scientific community will very interested if the speed of propagation of gravity turns out to be different from the speed of propagation of light. There will be so many articles and letters submitted to the scientific journals there will be an ink shortage if they try to print everything.
As a group those scientists are pretty smart. They'll know something revolutionary almost instantly. E-mails alone will clog the bandwidth for hours.