Run this from a WordPress plugin SVN checkout to see what has changed in trunk vs your stable tag

plugindiff.rb

#!/usr/bin/ruby
# NOTE: uses local diffs (MUCH faster). So make sure you've `svn up`d.

path = `svn info`[/Working Copy Root Path: (.*)\n/, 1]
stable_tag = nil
File.open path + '/trunk/readme.txt', 'r' do |file|
	while line = file.gets
		break if stable_tag = line[/stable tag: ?(.*)\n/i, 1]
	end
end

print `diff -ur -x '.svn' #{path}/tags/#{stable_tag}/ #{path}/trunk/` + "\n"