...this year in states that play spring softball? I only have a 2003 rule book with me, and it says nothing on the matter.

Yes. The 2004 NFHS rule book has dropped the DH and added DP/FLEX. It is rule 3-3-6.

From the NFHS website:

The National Federation of State High School Associations (NFHS) Softball Rules Committee adopted the designated player/FLEX rule at its annual meeting June 8-9 in Indianapolis, Indiana.

The change to Rule 3-1-5 replaces the designated hitter (DH) rule with the designated player (DP)/FLEX rule. Under the rule change, the role of the offensive player is never terminated. It is now possible for a team to go from 10 to nine players and back to 10 players any number of times during the game. The DP and the FLEX (defensive player for whom the DP is batting) now also have the option of playing defense at the same time. The DH rule did not allow for the offensive player, the DH, and the player for whom she was batting, to play defense simultaneously.

“The DP/FLEX rule is not mandatory, but optional, and provides coaches with more flexibility in their lineups,” said Mary Struckhoff, NFHS assistant director and liaison to the NFHS Softball Rules Committee. “A coach can elect not to use the DP/FLEX at all, use it as he or she previously used the DH, or use it to its fullest extent. Five states (Arizona, Indiana, Minnesota, New Mexico and Pennsylvania) experimented with the DP/FLEX rule last year and provided the committee with positive feedback regarding its implementation.”

http://www.nfhs.org