Hi,
I've uploaded image pyramids with the Blue Marble data, you can get them from http://etch.opengeo.org/bluemarble/
There are also two demos so that you can look at the data first. This is essentially the output of Part 2 of the Blue Marble HowTo [1]
--
Arne Kepp
OpenGeo - http://opengeo.org
Expert service straight from the developers
1: http://geoserver.org/display/GEOSDOC/Load+NASA+Blue+Marble+Data