Just seen this today:
http://nfhs.org/press/lacrosse_rules_changes03.html
There are four main changes:
First ball retrievers are no longer needed as long as there are at least 4 balls across the end line set back 5 yards. This does not seem to be that big of a change.
Second is that if any person receives two unsportsmanlike penalties they are ejected. It seems that both can be only one minuets long. (Before an ejection foul was three minuets long). How ever this is not 100% clear.
Third is that goalies now have 5 seconds to reenter the crease on any restart. This was normally done in games I have seen and imagine was normally done in general.
Fourth is that the ball will be placed at the center X on all offside penalties where the ball was on the defensive half of the field of the offended team.
The Rules Committee also identified three Points of Emphasis for 2003-04: sportsmanship, mouth guards and playing field specifications.
The big two seem to be the second and forth rule changes.
Generally benign stuff unless the second unsportsmanlike foul needs to be a 3 minute long penalty.