Am I correct in saying that as of April 1st, 2006 OSHA adopted the NFPA safety requirements regarding arc-flash?

I am not aware of any formal acceptance of a recent version of NFPA 70E by OSHA.
OSHA has been enforcing the latest version of NFPA 70E, adopted or not, because it is considered to be a consensus standard and is used to determine safety compliance.
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=24617