Here's what I know, perhaps any NWA employees can share as well.

Mainline uniforms change March 31.

March 30, 2009: Domestic equipment and product integration with minor
modifications to FC/EY services

April 1, 2009: New flying for pre-merger Northwest crews on Delta routes
(cross fleeting... ie NWA 744 ATL-HNL etc...).

June 1, 2009: International service equipment integration with re-branding of
World Business Class (WBC) to BusinessElite (BE)
(only minor changes to service delivery processes at this time)