The pitching rules for Little League are ever changing and this year (2008) there have been major changes.

A pitcher who delivers one or more pitches in a game cannot play the position of catcher for the remainder of that day.
Regulation VI (c) states:
11-12 85 pitches per day*
9-10 75 pitches per day*

*If a pitcher reaches the limit imposed in Regulation VI (c) for his/her league age while facing a batter, the pitcher may continue to pitch until any one of the following conditions occurs: 1. That batter reaches base; 2. That batter is put out; 3. The third out is made to complete the half-inning.

20 pitches or less: A pitcher can pitch the next day and the next game.
21-40 pitches: 1 calendar days rest
41-60 pitches: 2 calendar days rest and a games rest
60+ pitches: 3 calendar days rest and a games rest

A violation of these rules can result in a protest (See Rule 4.19 concerning protests)