The GPM core satellite has been rolled out on its H-IIA launch vehicle to the launch pad at Tanegashima Space Center in southern Japan for a 12:37 p.m. CST launch. It has a 1 hour launch window (12:37 to 1:37 p.m. CST).
The launch of GPM was delayed about a half hour due to slight concerns over a possible collision with the International Space Station, since its ~400 km altitude orbit will be very similar to the ISS.
Here’s the NASA TV coverage, which has some nice animations, spacecraft integration video, and will go live as launch approaches:
UPDATE: The GPM core satellite has reached orbit and the solar arrays have been deployed. So far so good.