It has been done!!! Sprint is "releasing" the official 2.1 update for the Samsung Moment tomorrow, 14 May 2010.
It has been installed and rooted on my own phone, as well as others.
This is the official download. The .tar can be loaded from the old Sprint CL14 updater. The joeykrim recovery HAS to be installed from the old updater, as the new one will not recognise it.