Final COBRA Regulations have been issued by the Department of Labor. You can access the Press Release announcing the regulations here and the Model Notices here. Regarding the effective date, the DOL states:
In order to give plans enough time to modify their notice procedures, the new rules will be effective the first plan year that begins six months after publication of the rules in the Federal Register. [The publication date is May 26, 2004.] Before that date, plans may rely on either the proposed rules or the final rules (including the model forms as proposed or as finalized) to meet their COBRA notice obligations.