Until 2008, there are no rules changes. The Rules of Golf are changed only in Presidential election years (obviously every 4 years). In the meantime, some rules are occasionally written a little clearer but there are not changes except for every 4 years when the R&A and USGA meet to discuss proposed rules changes.

How a proposed rule becomes a "law" (schoolhouse rock of Rules of Golf)...

http://www.usga.org/playing/rules/changes_rules.html