The 2010 NPPL official rule book has been released. To download your copy, go HERE or to nppl.com. First thing after i downloaded my copy, I went through on the prohibitive color ruling.
5.01 Protected Color. Players’ uniforms may not contain the color orange, which is reserved as the “Protected Color” for paint.
8. Other Equipment
10. Prohibited Equipment
Looks like they do allow yellow equipment (jerseys, pants, goggles) except on loaders. Let's see if MY-NPL would follow on this 'new' ruling.
I made a post related to this issue last year. You can check it out here http://villainpaintball.blogspot.com/2009/11/no-more-yellow.html