I just rechecked Delta's web site and the change is effective on April 3, 2005.
"In First Class, Delta will continue to offer complimentary meal service on flights longer than 3½ hours and in select business markets on flights less than 3½ hours, including flights between Atlanta and Boston, New York’s LaGuardia and John F. Kennedy (JFK) airports, and between Cincinnati and Boston."
It looks like that LGA-ATL route will still be serving food after the "new expanded snack service" goes into effect.
ENJOY!!!!