As the subject says, I've added a package that adds the new RPM macros that Stanislav has created for 10.3+ to GNOME:Community. This provides the same macros for 10.2 and older.
Simply add this to your spec file and you can use roughly the same spec file across the versions:
%if %suse_version <= 1020 BuildRequires gconf2-rpm-macros %endif
If you include this within the %if statement then the spec file will normally be exactly the same throughout with no more %suse_version checks required
%define _prefix /opt/gnome %define _sysconfdir /etc%_prefix
Of course, there will be some exceptions to that but not many :)